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Nuclear Nonproliferation

Nuclear-Weapon-Free Zones (NWFZ) At a Glance

July 2017

Press Contacts: Kelsey Davenport, Director for Nonproliferation Policy, (202) 463-8270 x102


What is a Nuclear-Weapon-Free Zone?

A nuclear-weapon-free zone (NWFZ) is a specified region in which countries commit themselves not to manufacture, acquire, test, or possess nuclear weapons. Five such zones exist today, with four of them spanning the entire Southern Hemisphere. The regions currently covered under NWFZ agreements include: Latin America (the 1967 Treaty of Tlatelolco), the South Pacific (the 1985 Treaty of Rarotonga), Southeast Asia (the 1995 Treaty of Bangkok) Africa (the 1996 Treaty of Pelindaba) and Central Asia (the 2006 Treaty of Semipalatinsk).


Initial efforts to create an area free of nuclear weapons began in the late 1950s with several proposals to establish such a zone in Central and Eastern Europe. Poland offered the first proposal-named the Rapacki Plan after the Polish foreign minister-in 1958. The Rapacki Plan sought to initially keep nuclear weapons from being deployed in Poland, Czechoslovakia, West Germany, and East Germany, while reserving the right for other European countries to follow suit. The Soviet Union, Sweden, Finland, Romania, and Bulgaria also floated similar proposals. All these early efforts, however, floundered amidst the U.S.-Soviet superpower conflict, although the Rapacki Plan would serve as a model to the nuclear-weapon-free zones that were eventually set up in other regions of the globe.

Article VII of the nuclear Nonproliferation Treaty (NPT), which entered into force in 1970, affirms the right of countries to establish specified zones free of nuclear weapons. The UN General Assembly reaffirmed that right in 1975 and outlined the criteria for such zones. Within these nuclear-weapon-free zones, countries may use nuclear energy for peaceful purposes.

Protocol for Nuclear Weapon States

Each treaty establishing a nuclear-weapon-free zone includes a protocol for the five nuclear-weapon states recognized under the NPT-China, France, Russia, the United Kingdom, and the United States-to sign and ratify. These protocols, which are legally binding, call upon the nuclear-weapon states to respect the status of the zones and not to use or threaten to use nuclear weapons against treaty states-parties. Such declarations of non-use of nuclear weapons are referred to as negative security assurances. For more information, see Nuclear Declaratory Policy and Negative Security Assurances.

However, the five nuclear-armed countries have at times signed and ratified a NWFZ protocol and declared conditions reserving the right to use nuclear weapons in certain scenarios against parties to a nuclear-weapon-free zone. For instance, the United States signed the protocol for the African nuclear-weapon-free zone in April 1996 with a declaration that it would reserve the right to respond with all options, implying possible use of nuclear weapons, to a chemical or biological weapons attack by a member of the zone. None of the nuclear-weapon states have signed the relevant protocol for the treaty creating a zone in Southeast Asia because of concerns that it conflicts with the right of their ships and aircraft to have freedom of movement in international waters and airspace and problems with the definitions of territory, since includes exclusive economic zones and continental shelves. The other three zones do not explicitly rule out the transit of nuclear weapons by nuclear-weapon states through the zones, and the general practice of nuclear-weapon states is not to declare whether nuclear weapons are aboard their vessels.

In addition to nuclear-weapon-free zones, there are treaties and declarations, which are not covered by this fact sheet, banning the deployment of nuclear weapons in Antarctica, Mongolia, on the seabed, and in outer space.

Basic Elements of Nuclear-Weapon-Free Zone Treaties

Duration: The treaties are to remain in force indefinitely. Yet, each treaty includes a withdrawal option for states-parties. With the exception of the Treaty of Tlatelolco, which simply requires three months' advance notice before a withdrawal can take effect, all the NWFZ treaties require 12 months' advance notice for a state-party to end its treaty obligations.

Conditions: None of the treaties can be subjected to conditions by its non-nuclear-weapon states-parties.

Verification: Each state-party adopts comprehensive safeguards administered by the International Atomic Energy Agency (IAEA), which verifies that states-parties are not pursuing nuclear weapons illicitly. The Central Asian NWFZ goes a step further in requiring that states in the region adopt the IAEA's Additional Protocol, which provides for expanded monitoring.

Territory Covered: Each zone applies to the entire territories of all of its states-parties. Territory is understood to include all land holdings, internal waters, territorial seas, and archipelagic waters. The Latin American treaty also extends hundreds of kilometers from the states-parties' territories into the Pacific and Atlantic Oceans, but the nuclear-weapon states, citing their freedom at sea, assert that this does not apply to their ships and aircraft that might be carrying nuclear weapons. A dispute also exists over the inclusion of the Chagos Archipelago, which includes the U.S. military base at Diego Garcia in the Indian Ocean, as part of the proposed African nuclear-weapon-free zone. Neither the United States nor the United Kingdom recognizes Diego Garcia as being subject to the Pelindaba Treaty.

The Treaty of Tlatelolco (Latin America and the Caribbean)

Opened for signature: February 14, 1967
Entered into force: October 23, 2002[1]




Antigua and Barbuda

October 11, 1983

October 11, 1983


September 27, 1967

January 18, 1994


November 29, 1976

April 26, 1977


October 18, 1968

April 25, 1969


February 14, 1992

November 9, 1994

Bolivia (Plurinational State of)

February 14, 1967

February 18, 1969


May 9, 1967

January 29, 1968


February 14, 1967

October 9, 1974


February 14, 1967

August 4, 1972

Costa Rica

February 14, 1967

August 25, 1969


March 25, 1995

October 23, 2002


May 2, 1989

June 4, 1993

Dominican Republic

July 28, 1967

June 14, 1968


February 14, 1967

February 11, 1969

El Salvador

February 14, 1967

April 22, 1968


April 29, 1975

June 20, 1975


February 14, 1967

February 6, 1970


January 16, 1995

January 16, 1995


February 14, 1967

May 23, 1969


February 14, 1967

September 23, 1968


October 26, 1967

June 26, 1969


February 14, 1967

September 20, 1967


February 15, 1967

October 24, 1968


February 14, 1967

June 11, 1971


April 26, 1967

March 19, 1969


February 14, 1967

March 4, 1969

Saint Kitts and Nevis

February 18, 1994

April 18, 1995

Saint Lucia

August 25, 1992

June 2, 1995

Saint Vincent and the Grenadines

February 14, 1992

February 14, 1992


February 13, 1976

June 10, 1977

Trinidad and Tobago

June 27, 1967

December 3, 1970


February 14, 1967

August 20, 1968

Venezuela (Bolivarian Republic of)

February 14, 1967

March 23, 1970

Protocol ratification by nuclear-weapon states: 



States Ratified

Protocol I

Jurisdictional responsibility

France, United Kingdom, United States

Protocol II

Negative security assurances

China, France, United Kingdom, United States, Soviet Union[2]


The Treaty of Rarotonga (South Pacific)

Opened for signature: August 6, 1985
Entered into force: December 11, 1986





August 6, 1985

December 11, 1986

Cook Islands

August 6, 1985

October 28, 1985


August 6, 1985

October 4, 1985


August 6, 1985

October 28, 1986


July 17, 1986

April 13, 1987

New Zealand

August 6, 1985

November 13, 1986


August 6, 1985

May 12, 1986

Papua New Guinea

September 16, 1985

September 15, 1989


August 6, 1985

October 20, 1986

Solomon Islands

May 29, 1987

June 27, 1989


August 2, 1996

December 18, 2000


August 6, 1985

January 16, 1986


September 16, 1995

February 9, 1996

Protocol ratification by nuclear-weapon states: 



States Ratified

Protocol I*

Prohibition on the manufacture, stationing and testing of any nuclear explosive device

France, United Kingdom

Protocol II

Negative security assurances

China, France, United Kingdom, Soviet Union[2]

Protocol III

Ban on nuclear testing in nuclear-weapon-free zone

Soviet Union[2]

*(open only to France, the United Kingdom and the United States)


The Treaty of Bangkok (Southeast Asia)

Opened for signature: December 15, 1995
Entered into force: March 27, 1997




Brunei Darussalam

December 15, 1995

November 22, 1996


December 15, 1995

March 27, 1997


December 15, 1995

April 10, 1997

Lao People’s Democratic Republic

December 15, 1995

July 16, 1996


December 15, 1995

October 11, 1996


December 15, 1995

July 17, 1996


December 15, 1995

June 21, 2001


December 15, 1995

March 27, 1997


December 15, 1995

March 20, 1997


December 15, 1995

November 26, 1996

Protocol ratification by nuclear-weapon states: 

  • None. Five nuclear weapons states and ASEAN members met in July 2012 to sign the treaty protocol. The treaty commission, however, postponed the signing of the protocol until November, requesting more time to review reservations that several of the NWS indicated that they would attach during ratification.


The Treaty of Pelindaba (Africa)

Opened for signature: April 11, 1996
Entered into force: July 15, 2009





April 11, 1996

February 11, 1998


April 11, 1996

June 20, 2014


April 11, 1996

September 4, 2007


June 9, 1998

June 16, 1999

Burkina Faso

April 11, 1996

August 27, 1998


April 11, 1996

July 15, 2009


April 11, 1996

September 28, 2010

Cape Verde

April 11, 1996


Central African Republic

April 11, 1996



April 11, 1996

January 18, 2012


April 11, 1996

July 24, 2012


January 27, 1997

November 26, 2013

Cote D’Ivoire        

April 11, 1996

July 28, 1999

Democratic Republic of the Congo

April 11, 1996



April 11, 1996



April 11, 1996


Equatorial Guinea


February 19, 2003


April 11, 1996



April 11, 1996

March 13, 2008


April 11, 1996

June 12, 2007


April 11, 1996

October 16, 1996


April 11, 1996

June 27, 2011


April 11, 1996

January 21, 2000


April 11, 1996

January 4, 2012


April 11, 1996

January 9, 2001


April 11, 1996

March 14, 2002


July 9, 1996



April 11, 1996

May 11, 2005



December 23, 2003


April 11, 1996

April 23, 2009


April 11, 1996

July 22, 1999


April 11, 1996

February 24, 1998


April 11, 1996

April 24, 1996


April 11, 1996

August 28, 2008


April 11, 1996

March 1, 2012


April 11, 1996

February 22, 2017


April 11, 1996

June 18, 2001


April 11, 1996

February 1, 2007

Sao Tome & Principe

July 9, 1996



April 11, 1996

October 25, 2006


July 9, 1996

May 23, 2014

Sierra Leone

April 11, 1996



February 23, 2006


South Africa

April 11, 1996

March 27, 1998


April 11, 1996



April 11, 1996

July 17, 2000


April 11, 1996

July 18, 2000


April 11, 1996

October 7, 2009


April 11, 1996


United Republic of Tanzania

April 11, 1996

June 19, 1998


April 11, 1996

April 6, 1998


April 11, 1996

April 6, 1998

 Protocol ratification by nuclear-weapon states: 



States Ratified

Protocol I

Negative security assurances

China, France, Russia, United Kingdom

Protocol II

Ban on nuclear testing in zone

China, France, Russia, United Kingdom

Protocol III*

Jurisdictional responsibility


*(open only to France and Spain)


Central Asian Nuclear-Weapon-Free Zone Treaty

Opened for signature: September 8, 2006
Entered into force: March 21, 2009 





September 8, 2006

February 19, 2009


September 8, 2006

July 27, 2007


September 8, 2006

January 13, 2009


September 8, 2006

January 17, 2009


September 8, 2006

May 10, 2007

 Protocol ratification by nuclear-weapon states: 



States Ratified

Protocol I*

Negative security assurances

China, France, Russia, United Kingdom

*United States signed but has not ratified


1. The treaty specified that the full zone would not enter into force until it was ratified by all states within the zones. That did not occur until Cuba ratified the treaty in 2002. However, the treaty permitted individual states to waive that provision and declare themselves bound by the treaty, which many did beginning in 1968.

2. Russia is recognized as inheriting the Soviet Union's treaty commitments.

Nuclear/Ballistic Missile Nonproliferation

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PRESS RELEASE: Iran Nuclear Deal Still Working Effectively



Statement from Kelsey Davenport, director for nonproliferation policy

For Immediate Release: July 13, 2017

Media Contacts: Kelsey Davenport, director for nonproliferation policy, (202) 463-8270 ext. 102; Daryl G. Kimball, executive director, (202) 463-8270 ext. 107 

(Washington, D.C.)—Two years ago on July 14, six world powers and Iran finalized an historic nuclear agreement with Tehran that removed the threat of an Iranian nuclear weapon. The nuclear deal, known as the Joint Comprehensive Plan of Action, has proven to be a nonproliferation success. The agreement has significantly restricted Iran’s nuclear activities and imposed an intrusive monitoring and verification regime. The threat of a nuclear-armed Iran no longer looms over the international community.
Despite the success of the deal, some policymakers in Washington are recklessly urging the Trump administration to abandon the agreement on the basis of inaccurate claims that Tehran is violating the accord. Six reports from the International Atomic Energy Agency demonstrate that Iran is meeting its commitments and the Trump administration certified in April that Iran is living up to its end of the deal.
Before taking unilateral steps that risk the success of the agreement, Washington should carefully consider the consequences. Abandoning an agreement that is verifiably blocking Iran’s pathways to nuclear weapons is irresponsible and dangerous. It would further destabilize the region, and could open the door to a nuclear-armed Iran or increase the prospect of a costly war in the Middle East. Additionally, pulling out of a multilateral agreement that benefits international security sends the message to U.S. allies and partners that Washington cannot be trusted to follow through on its commitments.
Given the current instability in the Middle East, it is now more vital than ever that Washington continue to support the nuclear deal with Iran and look for options to build on the agreement. Full implementation of the accord benefits U.S. national security and international efforts to prevent the spread of nuclear weapons.
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Statement from Kelsey Davenport, director for nonproliferation policy

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Amendment on CTBTO Funding Would Undermine Global Test Ban



Volume 9, Issue 4, July 2017

Unfortunately, a small but influential group of Republican lawmakers are seeking to cut U.S. funding for the Comprehensive Test Ban Treaty Organization (CTBTO) and undermine international support for the Comprehensive Test Ban Treaty (CTBT) and the global nuclear test moratorium.

Sen. Tom Cotton (R-Ark.) and Rep. Joe Wilson (R-S.C.) introduced legislation on Feb.7 to “restrict” funding for the CTBTO.

The House approved the language as an amendment by Wilson to the National Defense Authorization Act; the Senate will consider a similar amendment from Sen. Cotton when it considers the NDAA later this week.*

The amendment purports not to restrict U.S. funding specifically for the CTBTO's International Monitoring System, but in practice any significant reduction in U.S. technical and financial support for the CTBTO would:

  • adversely impact the organization’s ability to operate and maintain existing nuclear test monitoring stations. This is due to the fact that a wide range of organization’s personnel and assets directly or indirectly support the IMS. This includes staff time and technical support for the International Data Centre in Vienna, which processes information provided by IMS operations; and
  • prompt other states to restrict their funding for the CTBTO or possibly withhold data from CTBTO monitoring stations that are based in their territory, thus undermining the capabilities of the system to detect and deter clandestine nuclear testing.

U.S. Secretary of State Rex Tillerson speaks with Italian Foreign Minister Angelino Alfano and European Union High Representative for Foreign Affairs Federica Mogherini during the April 2017 G7 foreign ministers meeting in Italy. [State Department photo/ Public Domain]The Wilson amendment would run counter to the policy position articulated by Secretary of State Rex Tillerson, who joined with his G7 foreign ministerial counterparts to extoll the value of the CTBTO in their April joint communique on nonproliferation and disarmament. They said in part:

We believe that all States should maintain all existing voluntary moratoria on nuclear weapon test explosions or any other nuclear explosion, and those States that have not instituted such moratoria should do so. The verification regime being established by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization, in particular the International Monitoring System and International Data Centre, has proven its effectiveness by providing substantive and reliable data on the nuclear tests conducted by North Korea. We strongly encourage all interested States to complete the IMS as a matter of priority.

The proposed Wilson amendment also seeks to undermine the U.S. obligation—as a signatory to the 1996 Comprehensive Test Ban Treaty—not to conduct nuclear test explosions. The amendment calls on Congress to declare that the September 2016 UN Security Council Resolution 2310 does not “obligate…nor does it impose an obligation on the United States to refrain from actions that would run counter to the object and purpose” of the CTBT, which President Bill Clinton signed in 1996.

Contrary to what the Cotton-Wilson bill implies, Resolution 2310 (which was endorsed by 42 states, including Israel) does not impose any new obligations on the United States. Rather, it:

  • encourages states to “provide the support required” to the CTBTO and the IMS, and urges states to refrain from nuclear testing and urges those states that have not ratified to do so; and
  • also takes note of a September 15 joint statement by the five permanent Security Council members that formally “recognized” that a nuclear explosion would “defeat the object and purpose of the CTBT.” 

The G7 Foreign Minsters’ April 11 Joint Communique—endorsed by Tillerson—also “recalls" UN Security Council Resolution 2310 as an important contribution to the effort to ensure all states that have signed the CTBT do not go back on their promise not to conduct nuclear weapon test explosions. 

However, if Congress were to assert that the United States is not required to respect our obligations as a CTBT signatory not to conduct nuclear test explosions, it would signal to other states that that the United States may be seeking to back out of its commitment to a global and verifiable nuclear test ban and is considering the resumption of nuclear testing.

That’s not a smart move. With North Korea threatening to conduct a sixth nuclear test explosion, it is essential that the United States reinforce, not undermine, the global nuclear testing taboo

Backing off the United States' historically strong commitment to halting nuclear testing by any country at this time could trigger a dangerous chain reaction by other nuclear-armed states and would run afoul of key U.S. allies who strongly oppose nuclear testing and who support the CTBT. U.S. financial support to the CTBTO is critical to detect and deter nuclear weapons testing and it enhances national and international security—and should not be subjected to the restrictions proposed in the Wilson amendment.—DARYL G. KIMBALL, executive director

*This sentence was updated July 17, 2017 to reflect that the House amendment by Wilson was adopted by a voice vote.


Sen. Tom Cotton (R-Ark.) and Rep. Joe Wilson (R-S.C.) introduced legislation on Feb.7 to “restrict” funding for the CTBTO. The bill will be offered as a floor amendment by Wilson to the House version of the National Defense Authorization Act, which is being considered this week.

Nuclear Weapons Ban Treaty Adopted

July/August 2017
By Alicia Sanders-Zakre

The formal adoption of the first legally binding global treaty prohibiting nuclear weapons possession, use, and threat of use was greeted with widespread approval from the international community, with the exception of the nuclear-weapon states and their defense treaty allies who dismissed the accord as irrelevant and even potentially dangerous.

Delegates and observers applaud at the United Nations moments after the Treaty on the Prohibition of Nuclear Weapons is adopted July 7 by a vote 122 in favor, 1 against, and 1 abstention.  (Photo credit: Alicia Sanders-Zakre/Arms Control Association)On July 7, 122 non-nuclear-armed states voted to adopt the Treaty on the Prohibition of Nuclear Weapons following four weeks of talks at a special UN conference. Supporters hailed it as a new tool to strengthen norms against nuclear weapons use and said it can, in tandem with the nuclear Nonproliferation Treaty (NPT), discourage other states from seeking to obtain nuclear weapons and spur further action on nuclear disarmament.

“After many decades, we have managed to sow the first seeds of a world free of nuclear weapons,” declared Costa Rican Ambassador Elayne Whyte Gómez, president of the conference.

The Netherlands, the only NATO ally participating, voted against the treaty, and Singapore abstained. No nuclear-armed state participated, and the United States actively opposed the effort. The treaty has provisions governing how nuclear-weapon states could join the treaty, verifiably giving up their arsenals, although treaty supporters recognized that is not likely to happen anytime soon.

Even so, the treaty, which opens for signature when the UN General Assembly convenes in September, represents a powerful international statement at a time of renewed anxieties over potential nuclear weapons use. Dell Higgie, New Zealand’s ambassador for disarmament,  applauded the “strong and balanced treaty” in a July 8 email to Arms Control Today, commenting that the negotiations “put nuclear disarmament and the humanitarian spirit in the spotlight again.”

The negotiations were authorized in December 2016 by the UN General Assembly, which called for a “legally binding instrument to prohibit nuclear weapons, leading towards their total elimination.” Such talks had been sought by states and disarmament advocates long frustrated by what they regard as the nuclear-weapon states’ lack of progress on their existing NPT disarmament obligations, by the growing risk of intentional or accidental nuclear weapons use, and by the recognition of the catastrophic humanitarian consequences of a nuclear detonation. (See ACT, June 2017.)

“We hope that today marks the beginning of the end of the nuclear age,” Beatrice Fihn, executive director of the International Campaign to Abolish Nuclear Weapons, said in a July 7 statement.

The effort and outcome united individuals such as Setsuko Thurlow, a survivor of the U.S. bombing of Hiroshima, and former U.S. Defense Secretary William Perry, who oversaw the U.S. nuclear force under President Bill Clinton.

Thurlow, who has spent her lifetime advocating nuclear abolition, brought many participants to tears as she called on them to “pause for a moment to feel the witness of those who perished in Hiroshima and Nagasaki.” Perry, who now warns of a nuclear abyss, applauded the treaty as “an important step towards delegitimizing nuclear war as an acceptable risk.”

“Though the treaty will not have the power to eliminate existing nuclear weapons, it provides a vision of a safer world,” Perry said in a July 7 statement.

A note of discord emerged as the negotiations concluded. The Netherlands called for a vote, instead of allowing adoption by consensus. The Dutch delegates explained that the treaty was incompatible with its obligations as a NATO member, had provisions that are not verifiable, and could undermine the NPT. Singapore abstained after provisions it sought were not adopted.

Outside the negotiation room, opposition was more stark. In a joint statement on July 7, the United States, the United Kingdom, and France strongly rejected the “purported ban” that they said will not result in “the elimination of a single nuclear weapon” since it fails to address the security concerns “that continue to make nuclear deterrence necessary.”

“We are disappointed at the ban negotiations, for the proposed treaty will be ineffective at best and may in fact be deeply counterproductive,” Chris Ford, special assistant to the president and senior director for weapons of mass destruction and counterproliferation on the U.S. National Security Council, said in a July 10 email to Arms Control Today. “We hope, however, that the more thoughtful of its supporters will join us in seeking genuinely effective measures related to ending nuclear arms races and fulfilling the objectives of the NPT.”

Ford said the Trump administration is engaged in “efforts to reduce nuclear dangers worldwide,” including through initiatives to strengthen the NPT; secure or eliminate nuclear materials “that might otherwise fall into the hands of terrorists and other rogue actors;” improve nuclear safety; counter threats to nuclear facilities; improve crisis communications between nuclear powers to reduce the risk of nuclear accident or miscalculation; and promote and maintain strategic stability through diplomatic engagement and “effective arms control.”

This agenda “includes a commitment, consistent with the NPT, to seeking to ease tension and strengthen trust between states in ways that will help reduce nuclear dangers and offer the best hope of fulfilling the NPT’s objectives,” he said.

Treaty Provisions

The treaty has a 24-paragraph preamble acknowledging the catastrophic humanitarian consequences of nuclear weapons use and the value of existing international disarmament agreements, including the NPT, the Comprehensive Test Ban Treaty, and nuclear-weapon-free-zone agreements, as well as the right of states-parties to peaceful nuclear energy applications.

States-parties are prohibited to use, threaten to use, develop, produce, manufacture, acquire, possess, stockpile, transfer, station, or install nuclear weapons or assist with any prohibited activities. Non-nuclear-weapon states are required to have, at a minimum, a comprehensive safeguards agreement with the International Atomic Energy Agency (IAEA).

A state-party must declare, when joining the treaty, whether it has eliminated a previous nuclear weapons program, currently has nuclear weapons, or holds anther country’s nuclear weapons on its territory. In the latter case, it must remove them when it signs the treaty.

A nuclear-weapon state can accede to the treaty and eliminate its nuclear weapons in one of two ways: it can join the treaty and then destroy its nuclear weapons, or destroy its nuclear weapons and then join the treaty. States that “destroy and join” must cooperate on verification with a “competent international authority” to be designated in the future. States that “join and destroy” must immediately remove nuclear weapons from operational status and submit a time-bound plan for their destruction within 60 days of joining the treaty.

The treaty requires any current or former nuclear weapons state that seeks to join the treaty to conclude a safeguards agreement with the IAEA to verify that nuclear materials are not diverted from peaceful to weapons purposes. The treaty also obligates states-parties to provide victim assistance and environmental remediation to those affected by nuclear weapons use and testing.

Biennial meetings of states-parties will address implementation and other measures. Review conferences will be held every six years. The treaty enters into force 90 days after the 50th state ratifies it.

Issues During Negotiations

The treaty underwent significant revisions during two sessions of often constructive but at times contentious negotiations. Language on declarations, safeguards, and treaty accession by nuclear-weapon states was the most heavily revised, largely for precision and clarity.

The biggest debates centered on whether to include controversial language on prohibitions and strengthening safeguards re­quirements. Whyte Gómez chose not to incorporate contested proposals into the final text in order to conclude a treaty with broad support. The failed measures include a proposal supported by Cuba and Iran for additional prohibitions on financing and transit of nuclear weapons, which Brazil and Mexico opposed. Sweden and Switzerland pushed for stronger safeguards requirements, specifically a reference to the IAEA Model Additional Protocol, but Brazil opposed making mandatory a previously voluntary agreement.

There was a last-minute debate on July 5 about removing the clause that permits withdrawal from the treaty, which Whyte Gómez ultimately decided to retain.

The Work Ahead

Supporting states hailed the achievement, even as many dele­gates acknowledged the treaty is only a step toward nuclear disarmament. The treaty “lays the foundation,” but adoption is “just the beginning,” Ambassador Thomas Hajnoczi, Austria’s permanent representative to the United Nations Office at Geneva, said in a statement after the vote.

The negotiators agreed to set 50 ratifying states as the threshold for the treaty’s entry into force, but they recognized the accord will have greater normative weight with the more states that join. Although most of the 122 states that voted to approve the treaty will likely sign this year, the ratification process will be more time consuming, especially if the major nuclear-armed states seek to dissuade key states from ratifying.

Under the terms of the accord, states-parties are obligated to press other states to “accept, approve or accede to” the treaty with a “goal of universal adherence.” Brazil was among those to hint at the challenge of reaching that goal, urging “a continued dialogue with those that did not join this treaty, including those with nuclear weapons.”—ALICIA SANDERS-ZAKRE

Nuclear Weapons Ban Treaty Adopted

New Nuclear Weapons Prohibition Treaty Marks a Turning Point



Statement by Daryl G. Kimball, executive director

For Immediate Release: July 7, 2017

Media ContactsDaryl G. Kimball, executive director, (202) 463-8270 ext. 107; Kingston Reif, director for disarmament policy, (202) 463-8270 ext. 104; Alicia Sanders-Zakre, research assistant, (202) 463-8270 x113

(United Nations, New York)—Today at United Nations headquarters, more than 130 states concluded negotiations on and adopted a new “legally-binding instrument to prohibit nuclear weapons.”

Photo credit: International Campaign to Abolish Nuclear WeaponsThe new Treaty on the Prohibition of Nuclear Weapons marks a new phase in the seven-decade-long effort to prevent nuclear war. For the first time since the invention of the Bomb, nuclear weapons development, production, possession, use, threat of use, and“stationing” of another country’s nuclear weapons on a states party's national territory are all expressly prohibited in a global treaty. The treaty also requires states to provide assistance to those affected by nuclear weapons use and testing.

While the treaty itself will not immediately eliminate any nuclear weapons, the treaty can, over time, further delegitimize nuclear weapons and strengthen the legal and political norm against their use. Steps aimed at reducing the risk of catastrophic nuclear weapons use are necessary and should be welcomed.

The new Treaty on the Prohibition of Nuclear Weapons aims to reinforce the key disarmament component (Article VI) of the 1968 Nuclear Non-Proliferation Treaty (NPT), which requires its 190+ states parties to “pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament.

Under the new treaty, states may not“test” nuclear weapons or any other nuclear explosive devices. This simply reinforces the 1996 Comprehensive Nuclear Test Ban Treaty (CTBT) which prohibits“any nuclear weapon test explosion or any other nuclear explosion” and has been signed by 183 states, including the United States, Russia, the United Kingdom, France, and China.

The new treaty, which was negotiated by a group of some 130 non-nuclear weapon states, is an expression of the deep concern about the enormous risks posed by nuclear weapons and the growing frustration with the failure of the nuclear-armed states to fulfill their nuclear disarmament commitments. The initiative underscores the need for thenuclear weapons states’ to meet their existing legal obligations to end the nuclear arms race and pursue disarmament and the catastrophic humanitarian consequences of nuclear weapons.

In our view, and in the view of many delegations, the final text of the Nuclear Weapons Prohibition Treaty should have been stronger. Key areas, particularly Article 3, which outlines the requirements for safeguards against nuclear weapons programs, could have been strengthened and improved.

While the new treaty usefully outlines key objectives for verifying disarmament by nuclear-armed states in the future, the new treaty only obligatesstates parties not possessing nuclear weapons to maintain or bring into force a Comprehensive Safeguards Agreement with the IAEA“at a minimum."

Unfortunately, the new Treaty on the Prohibition of Nuclear Weapons makes no specific reference to the value of more rigorous inspection procedures, known as the Additional Protocol or “AP+” measures, which is a goalthat states parties at this conference have already agreed to pursue in the context of the NPT. The 2000, 2010, and 2015 NPT Review Conference reports all stressed “that comprehensive safeguards and additional protocols should be universally applied once the complete elimination of nuclear weapons has been achieved.”The history of the Iraqi, North Korean, and Iranian nuclear programs shows that the IAEA safeguards regime must and has and will continue to evolve in order to effectively guard against clandestine nuclear weapons programs.

The new Treaty on the Prohibition of Nuclear Weapons is a historic step forward but, clearly, it is not an all-in-one solution to the dangers posed by nuclear weapons. Additional and difficult work lies ahead.

Prohibition treaty supporters, skeptics, and opponents must put aside their disagreements about the new agreement and find new and creative ways to come together to strengthen the nuclear disarmament and nonproliferation regime.

They must focus on advancing new and effective disarmament measures, while pursuing policies that ease the growing tensions between nuclear-armed states and increase the danger of nuclear weapons use.

Such measures include but are not limited to:

  • securing the remaining eight ratifications, including the United States, China, Iran and Israel, needed to bring the CTBT into force;
  • reviving the moribund U.S.-Russian arms control and risk reduction dialogue, including resolving U.S.-Russian treaty compliance disputes and extending the New START agreement beyond 2021;
  • bringing China, India, and Pakistan further into the nuclear risk reduction and disarmament process;
  • avoiding the introduction of new and destabilizing nuclear weapons systems and capabilities;
  • concluding an agreement on legally-binding negative nuclear security assurances for nonnuclear-weapon states;
  • continuing to implement and build upon the agreement between Iran and six world powers that verifiably limits its weapons-relevant nuclear activities; and
  • engaging in pragmatic and sustained diplomacy with North Korea, coupled with smart sanctions, to halt and reverse that country’sdangerous nuclear pursuits.

Nuclear weapons pose a global threat that demands global cooperation. Now is the time for stronger and smarter leadership from Washington, Moscow, and Beijing, as well as more active support from the world’s non-nuclear weapon states.


The Arms Control Association is an independent, membership-based organization dedicated to providing authoritative information and practical policy solutions to address the threats posed by the world's most dangerous weapons.


For the first time since the invention of the Bomb, nuclear weapons development, production, possession, use, threat of use, and“stationing” of another country’s nuclear weapons on a states party's national territory are all expressly prohibited in a global treaty.

Banning the Bomb—A Blog of the Nuclear Weapons Prohibition Talks

Alicia Sanders-Zakre will be tweeting and blogging throughout the Nuclear Weapons Prohibition Talks at the United Nations. Follow her real-time updates at twitter.com/azakre . Second Negotiating Session: June 15-July 7, 2017 UN Adopts Treaty Banning Nuclear Weapons July 7, 2017 Today by a vote of 122-1 with 1 abstention, states adopted a historic treaty prohibiting nuclear weapons at the United Nations in New York. The Netherlands voted against the treaty and Singapore abstained. Before adopting the treaty, Ambassador Elayne Whyte Gomez declared that “after many decades, we have managed to...

The Presidential Nuclear Initiatives (PNIs) on Tactical Nuclear Weapons at a Glance

July 2017

Contacts: Daryl Kimball, Executive Director, (202) 463-8270 x107; Kingston Reif, Director for Disarmament and Threat Reduction Policy, (202) 463-8270 x104

Near the Cold War’s end, leaders in Washington and Moscow made reciprocal unilateral pledges to substantially limit and reduce their nuclear weaponry, most notably their tactical or “battlefield” nuclear weapons, such as nuclear artillery shells. President George H.W. Bush initiated these commitments, collectively known as the Presidential Nuclear Initiatives (PNIs), in September 1991 in recognition of the break up of the Eastern bloc and out of concern for the Kremlin’s ability to maintain control of its vast nuclear arsenal as political changes swept the Soviet Union. By pledging to end foreign deployments of entire categories of U.S. tactical nuclear weapons, Bush hoped that leaders in Moscow would follow suit; and they did, at least in part. All Soviet nuclear weapons were reportedly successfully consolidated on Russian soil. Still, Washington alleges Moscow has not yet fulfilled all of its PNI destruction commitments. Meanwhile, Russia opposes the continued stationing of U.S. tactical nuclear gravity bombs in Europe, which the PNIs did not cover. Despite lingering concerns about each other’s tactical nuclear weapons, the two sides have not negotiated further reductions or transparency measures for these arms since the early 1990s.

U.S. Presidential Nuclear Initiatives:

On Sept. 27, 1991, Bush announced a raft of unilateral initiatives to limit and reduce the U.S. tactical nuclear weapons arsenal. Specifically, he pledged to:

  • withdraw to the United States all ground-launched short-range weapons deployed overseas and destroy them along with existing U.S. stockpiles of the same weapons; and
  • cease deployment of tactical nuclear weapons on surface ships, attack submarines, and land-based naval aircraft during “normal circumstances.” Implicitly, the United States reserved the right to redeploy these arms in a crisis.

Soviet/Russian Presidential Nuclear Initiatives:

On Oct. 5, 1991, Soviet President Mikhail Gorbachev responded to Bush’s speech with reciprocal Soviet measures. Specifically, Gorbachev committed to:

  • eliminate all nuclear artillery munitions, nuclear warheads for tactical missiles, and nuclear mines;
  • remove all tactical nuclear weapons from surface ships and multipurpose submarines. These weapons would be stored in central storage sites along with all nuclear arms assigned to land-based naval aircraft; and
  • separate nuclear warheads from air defense missiles and put the warheads in central storage. A “portion” would be destroyed.

On Jan. 29, 1992, Russian President Boris Yeltsin reaffirmed Gorbachev’s commitments and expanded on them in response to a second round of unilateral U.S. nuclear weapons cutbacks focused on strategic forces. (Following the Soviet Union’s Dec. 25, 1991 collapse, Russia assumed responsibility for the Soviet Union’s nuclear complex and arms control commitments.) Yeltsin said Russia would:

  • eliminate a third of its sea-based tactical nuclear weapons and half of its ground-to-air nuclear missile warheads; and
  • halve its airborne tactical nuclear weapons stockpile. Pending reciprocal U.S. action, the other half of this stockpile would be taken out of service and placed in central storage depots.


A precise accounting of U.S. and Soviet/Russian fulfillment of their tactical nuclear weapons PNIs is difficult because of ambiguity, then and now, surrounding the composition, size, and location of these arms. By 1991, the United States had nearly 5,000 tactical nuclear weapons deployed overseas, most of which were assigned to NATO. Estimates on the size of the Soviet tactical nuclear arsenal at that same time ranged widely from 12,000 to nearly 21,700 weapons.

The United States completed its proposed reductions and withdrawals of deployed tactical nuclear weapons in 1992. The elimination process was finished in 2003.

As a result of the PNIs, the U.S. withdrew and destroyed around 2,000 ground-launched nuclear artillery shells and short-range ballistic missiles, all TNWs on navy surface ships and attack submarines, and on land-based naval aircraft, destroyed all nuclear depth bombs, de-alerted strategic bombers, and cancelled planned nuclear systems. By the mid-1990s, the stockpile of TNWs fell to below 1,000 warheads. Between 1990 and the end of 1994 (when the START Treaty entered into force), the U.S. nuclear stockpile of active and inactive warheads fell from 21,392 to 10,979, a 50 percent reduction.

At a Dec. 21, 1991 conference at Alma-Ata, the Soviet Republics of Belarus, Kazakhstan, and Ukraine pledged to return all Soviet tactical nuclear weapons on their territories to Russia by July 1, 1992. All three states met their commitments despite the Soviet Union’s breakup four days after these pledges were made. Otherwise, Russia has released little information substantiating its PNI activities. At the May 2005 nuclear Nonproliferation Treaty Review Conference, Moscow announced that all Russian tactical nuclear weapons “are now deployed only within the national territory and are concentrated at central storage facilities of the Ministry of Defense.” In 2007, Colonel-General Vladimir Verkhovtsev remarked, “Russia particularly committed itself to removing tactical nuclear weapons from the ground forces completely. Those weapons were also cut by 50 percent in the Air Force, by 60 percent in missile defense troops and by 30 percent on nuclear submarines of the Russian Navy,” the general said.

 Still, the Department of State has publicly questioned Russia’s PNI record. Specifically, it noted in June 2005, “Russia has failed to state publicly the status of the elimination of its nuclear artillery munitions, nuclear warheads for air defense missiles, nuclear mines, or nuclear weapons on land-based naval aviation.” These concerns were not expressed in the 2017 State Department Compliance Report, however.

Current Status:

As of 2016, the United States possesses about 500 B61 gravity bombs, 150-200 of which deployed in five European countries (Belgium, Germany, Italy, the Netherlands and Turkey). As of 2017, Russia retains approximately 1850 nonstrategic weapons, all of which are stored on Russian territory.

Since the PNIs, the United States and Russia have not agreed on additional measures to share information on or limit their tactical nuclear weapons. The two countries agreed in March 1997 to explore measures relating to tactical nuclear weapons, but nothing came of this effort. In June 2005, Russia conditioned additional talks on tactical nuclear weapons to the U.S. withdrawal of its remaining nuclear weapons in Europe. The United States has said these weapons are deployed as part of NATO policy and that a decision to withdraw them would need to be taken by all alliance members. In 2005, Congress passed legislation calling on the Bush administration to investigate measures to help Russia account for and secure its tactical arms and assess whether tactical nuclear reductions with Russia should be pursued.

In 2010, the Barack Obama administration stated that it was the goal of the United States to seek further reductions in all types of U.S. and Russian nuclear weapons—strategic and nonstrategic, deployed or nondeployed—following the conclusion of the 2010 New START talks. The 2010 NATO Strategic Concept states that the goal of the alliance is to "seek Russian agreement to increase transparency on its nuclear weapons in Europe and relocate these weapons away from the territory of NATO members." officials insist that the U.S. should first withdraw all of its tactical nuclear weapons to its national territory. In the 2010 Nuclear Posture Review, the Obama Administration announced a unilateral retirement of the Navy’s stockpile of nuclear-armed submarine launched cruise missiles (SLCMs). 

In April 2010, then-Secretary of State Hillary Clinton stated that the U.S. could remove nuclear weapons from Europe in exchange for a reduction in the size of Russia’s nonstrategic nuclear weapons arsenal. In 2013, Obama gave a speech advocating for the U.S. to work with European allies and Russia to negotiate future reductions in nonstrategic nuclear weapons.

However, to date the United States and Russia have not commenced talks regarding additional cuts on nonstrategic weapons, and a range of arms control disputes threatens to continue to obstruct progress on the matter. Russia is unlikely to discuss cuts to its nonstrategic nuclear weapons arsenal until the United States removes nonstrategic nuclear forces from Europe and agrees to limitations of its ballistic missile defense program. 

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The UN Report on the Iran Deal Resolution: The Good, the Unclear, and the Troubling

The UN Secretary General’s biannual report on UN Security Council Resolution 2231 affirms Iran’s compliance with nuclear provisions of the 2015 agreement between Tehran and the P5+1 (China, France, Germany, Russia, the United Kingdom, and the United States), but raises concerns about Iran’s ballistic missile activity and compliance with UN restrictions. Resolution 2231 (July 2015) endorsed the nuclear deal known as the Joint Comprehensive Plan of Action (JCPOA), and lifted some UN sanctions, while maintaining the arms embargo on Iran and ballistic missile restrictions. In the recently...

Key Issues in Negotiations for a Nuclear Weapons Prohibition Treaty

June 2017

By John Burroughs

The outlines of a treaty to prohibit nuclear weapons, leading to their total elimination, emerged in late March during the first week of negotiations among diplomats representing about 130 governments. During a second session, to take place from June 15 to July 7 at the United Nations, a text will be negotiated, based on the May 22 draft by the president of the negotiating conference, Ambassador Elayne Whyte Gómez of Costa Rica. She aims for conference approval of a text by the end of that session.

Supporters of the International Campaign to Abolish Nuclear Weapons stand outside the United Nations on March 30 as negotiations were underway inside the building involving representatives of about 130 countries. (Photo credit: Clare Conboy/ICAN)The envisaged treaty would be a relatively simple one, prohibiting the development, stockpiling, and use of nuclear weapons but not containing detailed provisions relating to the verified dismantlement of nuclear arsenals and to governance of a world free of nuclear weapons. The basic intent is to codify the norms of nonuse and nonpossession of nuclear weapons in light of the humanitarian consequences of nuclear explosions and to contribute to the eventual achievement of the global abolition of the weapons. Issues related to elimination of nuclear weapons will largely be left to later negotiations, within or outside the treaty framework, because none of the states possessing nuclear arsenals are participating nor are almost all states in nuclear alliances with the United States.

The negotiations grew out of the initiative on the humanitarian impact of nuclear weapons use, particularly the governmental conferences in Oslo; Nayarit, Mexico; and Vienna in 2013 and 2014. During the 2016 UN open-ended working group on nuclear disarmament, deliberations led to adoption of the strategy of seeking a prohibition or ban treaty and identified many of its elements.

The UN General Assembly in December 2016 adopted a resolution1 to convene the negotiating conference, put forward by lead sponsors Austria, Brazil, Ireland, Mexico, Nigeria, and South Africa. Proponents have emphasized that, like regional nuclear-weapon-free-zone treaties, the prohibition treaty will be complementary to the nuclear Nonproliferation Treaty (NPT). Indeed, they observe, it will partially fulfill Article VI, which requires NPT states-parties to "pursue negotiations in good faith on effective measures relating to … nuclear disarmament."

During the first week, most governments endorsed the negotiation of a treaty focused on prohibition. The positions of countries such as Algeria and Cuba, although accepting the notion of a prohibition treaty, nonetheless in the sweep of their recommendations reflect the long-standing Non-Aligned Movement support for a convention addressing all aspects of nuclear disarmament.2 Malaysia noted that it has been a champion of that approach, having put forward a model convention with Costa Rica. Many countries continue to foresee a future comprehensive agreement on nuclear disarmament following a prohibition treaty. The resolution convening the negotiations generally recognizes in its preamble that "additional measures, both practical and legally binding, for the irreversible, verifiable and transparent destruction of nuclear weapons would be needed in order to achieve and maintain a world without nuclear weapons."3

Differences concerning scope remain even among strong proponents of the nuclear ban treaty process. In Mexico’s view, negotiators should focus on setting broad prohibitions on possession, acquisition, stockpiling, use, development, transfer, stationing and deployment, and assistance with prohibited acts. They should not venture into complex, time-consuming issues, including those, such as a prohibition on testing, potentially affecting how other legal instruments are interpreted and applied. Alexander Marschik, Austrian vice minister for foreign affairs, stated, "There is a risk that we want to achieve too much…. Please, stay together behind this one, narrow, clear objective: a legal prohibition of nuclear weapons." Reflecting this view, Austria proposed a set of prohibitions restricted to use, development, production, stockpiling, transfer, and assistance with prohibited acts.

On the other hand, South Africa stated that although "the instrument would clearly be more limited than a Nuclear Weapons Convention," it does not "support the idea of turning a simple political declaration into a legally-binding instrument. [It] is unlikely to be taken seriously by those who may choose to remain outside…. More comprehensive prohibitions would therefore be preferred in the form of an unambiguous legal text." New Zealand stated, "We must not, by the omission of any key nuclear weapon development-related activities, seem to create any ambiguity or leave open any possible gap in its coverage."

Variety of Issues

As these positions indicate, drafting the treaty is not as straightforward as might first appear. The participants are non-nuclear-weapon state-parties to the NPT, which bars their acquisition of nuclear weapons, and most are also parties to nuclear-weapon-free-zone treaties. In certain respects, however, the prohibition treaty likely will go beyond the NPT and the nuclear-weapon-free-zone treaties by imposing additional obligations.

Elayne Whyte Gómez (right), permanent representative of Costa Rica to the UN Office at Geneva and president of the United Nations conference to negotiate a nuclear weapons prohibition treaty, chairs a meeting of the conference March 30. (Photo credit: Rick Bajornas/UN)Moreover, the treaty will generally help establish a template for future nuclear disarmament, as well as provide for possible accession of nuclear-armed states after they have disarmed or subject to a time-bound disarmament obligation. Most negotiators also want to make it possible for states in alliances with nuclear-armed states to join the treaty, provided that the allied states end reliance on nuclear weapons. For these and other reasons, a variety of difficult issues will have to be resolved.

This survey of key issues facing negotiators at the second session addresses prohibitions relating to development and manufacture, possession and stockpiling, transit, and use and threat of use; a prohibition on assistance; implementation of the treaty and positive obligations, for example, relating to victims of use and testing of nuclear weapons; institutional issues, including how nuclear-armed states could join the treaty, and final clauses; and the framing of the treaty in its preamble.4

Development and Manufacture

During the first week of negotiations, there was wide support for including a prohibition on development of nuclear weapons as well as their manufacture and/or production. This would provide clarity as compared with the NPT, which only expressly prohibits "manufacture." It would also address a gap in the nuclear-weapon-free-zone treaties, not all of which contain a prohibition on development.5

Exactly what activities constitute development? It clearly includes engineering leading to production, but does it include research and design? The term "research" could embrace, for example, simply gaining knowledge about nuclear weapons. Accordingly, there may be reluctance to consider it as an activity of development or to prohibit it separately, as it is in two nuclear-weapon-free-zone treaties.6 The term "design," however, is intrinsically related to creation of a warhead and is a term in common use in the nuclear sphere, although it has not been specifically banned in existing treaties prohibiting and eliminating biological weapons, chemical weapons, landmines and cluster munitions.

A related subject of discussion was whether to include a separate prohibition on nuclear explosive testing. Austria and Mexico contended that testing would be covered by a development ban. Further, they said, a separate testing prohibition would raise issues of consistency with the nuclear Comprehensive Test Ban Treaty (CTBT). Brazil, Ireland, New Zealand, South Africa, and other states favored a prohibition. During a conference discussion with experts, physicist Zia Mian, co-director of the Program on Science and Global Security at Princeton University, explained that not all testing is for development; it may be conducted, for example, to confirm the reliability of a weapon. A complication is that a whole range of activities—computer simulation, hydrodynamic and laser fusion experiments, subcritical explosions—may be considered "testing," and Brazil, South Africa, and other states expressed the desire explicitly to prohibit such activities.

The above issues could be resolved by including definitions of "development" and other key terms. Yet, some states are opposed, observing that it would delay negotiations and that the NPT does not provide definitions. The issues probably also could be resolved in drafting the prohibitions. A prohibition of testing could be made identical with the CTBT prohibition.7 Also, the ban treaty almost certainly will include a provision stating that its terms do not limit or detract from obligations under the CTBT, NPT, and other treaties regulating nuclear weapons. Other activities could be proscribed in connection with the prohibition of development.

There are strong reasons for being reasonably comprehensive. The nuclear ban treaty will set a normative standard for individuals and for future disarmament. It is not only about the legal rules for states that become parties in the near term. Further, specificity will clarify what activities parties must not allow that contribute to nuclear weapons work carried out by states outside the treaty.

One aspect of a development prohibition that received little attention is that monitoring and verifying compliance would be challenging. There are numerous activities related to nuclear and military technology that may or may not be considered part of a nuclear weapons program.8 Additionally, if an activity is intended to further development of nuclear weapons, it may not be easily detectable by observers from outside a country or by authorities within the country committed to compliance. An example is computer simulations of nuclear explosions.

These problems would be difficult ones even under optimal circumstances. In the case of a nuclear ban treaty initiated by non-nuclear-weapon states, a comprehensive verification regime beyond what is already provided by the International Atomic Energy Agency (IAEA) and by the CTBT system is not envisaged. The treaty probably will affirm in some fashion that member-states are obligated to comply with IAEA safeguards agreements and certainly should do so. It should also be considered whether adherence to the additional protocol to safeguards agreements should be required, as Sweden advocated, or at least encouraged by the treaty.

Aside from the safeguarding of fissile materials and detection of nuclear explosive testing, verification of a development prohibition probably will not be possible over the near term. Monitoring will have to be done through peer review among states-parties, national intelligence, civil society monitoring, and whistleblowers, who ideally would be protected by the treaty. A mitigating factor is that, as a matter of global politics and implementation of the NPT, serious efforts at undertaking nuclear weapons programs draw much attention, even when not in violation of safeguards agreements. Inclusion of a prohibition will add a clear legal dimension to what is already a matter of intense scrutiny. In the event of accession of nuclear-armed states to the treaty, additional verification arrangements should be agreed.

Possession and Stockpiling

The nuclear ban treaty will include a prohibition on stockpiling, which is standard in weapons-prohibition treaties. In part, it will lay the groundwork for an obligation of nuclear-armed states to dismantle their arsenals. Also possible is a related prohibition on retention, which is found in existing treaties.

A prohibition on possession of nuclear weapons likely will also be part of a nuclear ban treaty. It is contained in the nuclear-weapon-free-zone treaties but not as such in other treaties prohibiting weapons. A prohibition on acquisition may be included in order to capture coming into possession by means other than manufacture. Some states seek to include a deployment prohibition. The fielding of nuclear forces is intrinsic to nuclear deterrence as practiced by possessor states. A deployment prohibition would explicitly reject that practice and underline that members of a nuclear ban treaty in no way must cooperate with the practice. A possible, related prohibition of stationing would similarly underline that treaty members may not host nuclear weapons, as certain members of NATO do under nuclear sharing arrangements.

In the same vein, a likely prohibition of transfer of nuclear weapons, applying in the first place to possessors of nuclear weapons who join the treaty, would also imply that a member of the treaty may not accept nuclear weapons from a possessor state outside the treaty. Such an action would be barred as well by a prohibition of acquisition.

The issue of nuclear weapons delivery vehicles received little attention from governments during the first week of negotiations, perhaps because making prohibitions applicable to delivery vehicles for states that have never had nuclear weapons seems unnecessary and unduly complicated. Yet, arms control experience in the U.S.-Soviet/Russian relationship indicates that control or elimination of delivery systems developed for nuclear weapons will be required for a successful global enterprise of eliminating existing nuclear arsenals. Also, a paragraph in the NPT preamble refers to "the elimination from national arsenals of nuclear weapons and the means of their delivery." The issue of delivery systems may be left aside for now and addressed in some way should nuclear-armed states later join the treaty.

Transit Prohibition

A prohibition on transit, supported by some states, would require treaty parties to be proactive, going beyond the requirements of the nuclear-weapon-free-zone treaties. It would require a state-party to ensure that nuclear weapons or their components do not traverse its territory and the air and water over which it has jurisdiction and control. In line with its minimalist approach, Austria opposed the inclusion of such a prohibition, which it said would require resolution of difficult practical issues such as demarcation of maritime and air space. Further, Austria maintained, a prohibition on assisting prohibited acts would bar granting of transit rights. Malaysia similarly stated that implementation of a prohibition on transit would be impractical and lead to technical discussions.

A counterargument is that all states are currently obligated by UN Security Council Resolution 1540 to adopt measures, including controls on transit and financing, to prevent nonstate actors from trafficking in nuclear, biological, and chemical weapons and their means of delivery, including related materials. A prohibition on transit of nuclear weapons, therefore, would not seem to increase the burden with respect to, for instance, commercial shipping. It still might raise issues with respect to activities of nuclear-armed states. On balance, inclusion of a prohibition on transit makes sense. Full implementation can be achieved over time based on experience and cooperation among treaty parties. In this respect and others, the regime could evolve.

Use and Threat of Use

The nuclear ban treaty will include a prohibition on use of nuclear weapons, probably on the model of the Chemical Weapons Convention (CWC), in which states-parties undertake "never under any circumstances" to use chemical weapons. Another element of the CWC, a prohibition of engagement in any military preparations to use the specified weapons, is worth considering. It would go toward capturing the actions of participating in nuclear war planning, which also could be specifically proscribed, as Algeria recommended. Such provisions would be relevant in the event that states in military alliances with nuclear-armed states join the ban treaty.

There was some division of views during the opening negotiations regarding whether to include language prohibiting the threat of use. There is no such prohibition in the CWC and other treaties prohibiting and eliminating weapons, and there is a strong tendency to model the nuclear ban treaty on existing treaties. Further, several states, including Austria, Mexico, Sweden, and Switzerland, contended that the UN Charter prohibition of the threat of force suffices. Mexico went so far as to say that a specific prohibition on threat of use would call into question the integrity and scope of the UN Charter prohibition.

Arguments on the other side are powerful, and numerous states supported inclusion of a threat prohibition. As Chile said, the threat of use of nuclear weapons is the very foundation of nuclear deterrence, which has allowed the continued existence of the weapons jeopardizing security and survival. Nothing similar can be said about the other weapons already prohibited by treaties. Although useful guides, those treaties need not be slavishly followed. Moreover, in time of armed conflict—the most likely time when a specific threat of use would be made—the standard view is that international humanitarian law is the primary body of law governing the conduct of warfare, not the UN Charter. The International Court of Justice has stated that a threat to commit an act that would violate international humanitarian law is itself illegal.

The ban treaty negotiations grew out of the initiative on the humanitarian impact of nuclear weapons use. This photograph shows the devastated city of Hiroshima after the atomic bomb was dropped by a U.S. Air Force B-29 on August 6, 1945. (Photo credit: Stringer/AFP/Getty Images)A prohibition of threat of nuclear weapons use in times of peace and war would apply and reinforce the UN charter and international humanitarian law, not somehow undermine them. Further, as South Africa said, "a clear ban" on the use or threat of use of nuclear weapons "would be key to the effort to delegitimize the concept of nuclear deterrence."9 Ecuador stated that a threat prohibition is necessary in order to show that the concept has no place in international law.

Assistance with Prohibited Acts

There was widespread support for the inclusion of a prohibition on assistance with prohibited acts. As formulated in the CWC, states may not "assist, encourage or induce, in any way, anyone to engage in any activity prohibited to a state-party" under the CWC. A similar prohibition in the Treaty of Tlatelolco, which established a nuclear-weapon-free-zone for Latin America and the Caribbean, requires states to "refrain from encouraging or authorizing, directly or indirectly, or in any way participating" in prohibited acts. Evidently, a prohibition along these lines would bar members of a nuclear ban treaty from cooperation or permitting cooperation relating to nuclear weapons in multiple ways with states outside the treaty. This could become relevant in circumstances now not foreseeable for any member of the treaty, but it would be particularly relevant to any state in a military alliance with a nuclear-armed state that joins the treaty.

In the view of some states, a prohibition on assistance with prohibited acts would extend to financing of nuclear weapons production, at least so far as the state’s own investments are concerned, as Ireland noted. Other states favored the inclusion of a specific prohibition on financing. Implementation of such a prohibition could be complex and demanding, especially if it requires states to regulate actions of persons under its jurisdiction. Still, over time it would be possible to develop a common understanding of what is entailed. It is certain that civil society will be calling on states in a future ban treaty to adopt national measures to prevent financing of nuclear weapons activities, whether or not a specific prohibition is included.

Implementation and Positive Obligations

Some support was expressed during the first week of negotiations for a provision similar to that found in other treaties requiring states to take appropriate measures to prevent any prohibited activity undertaken by persons or on territory under its jurisdiction and control. Another obligation receiving some support would require states to report on their implementation of the treaty. Support was also expressed for an obligation of international cooperation and assistance in relation to states’ implementation of the treaty.

Based on precedents set by the treaties on landmines and cluster munitions, nuclear ban treaty advocates have called for positive obligations of states in relation to assistance to victims.10 States are wary of taking on such obligations, especially given the absence of the nuclear-armed states that have been responsible for harm to individuals and the environment arising from testing and use. Still, there is widespread support for a recognition of the rights of victims, at least in the preamble but perhaps as an obligation. This is natural because the negotiations have grown out of the conferences on the humanitarian consequences of nuclear explosions. Some support was also expressed for positive obligations on environmental remediation, disarmament education, and awareness raising of nuclear weapons risks.

Institutional Arrangements and Final Clauses

Many states supported providing for periodic review conferences of a treaty. Brazil also proposed providing for possible extraordinary sessions, which could negotiate a general plan for destruction of nuclear arsenals and measures related to a non-discriminatory verification regime.

There was also support for establishing an administrative body, which could prepare review conferences, assist states with implementation, and promote treaty aims. Based on the initial discussions, it likely would be quite modest in scope. As noted, at the outset there likely will not be a monitoring or verification capability focused on non-nuclear-weapon states’ implementation beyond what any reporting requirement and review conference assessment provide and the existing roles of the IAEA and the CTBT system.

Discussion of provisions for nuclear-armed states to join the treaty reflected two premises: All states are welcome and encouraged to become parties, and the treaty aims to contribute to the establishment of a world free of nuclear weapons. Yet, nuclear-armed states becoming parties to the treaty is entirely theoretical at this point. If they do decide to eliminate their arsenals, they may do so without joining the treaty. Accordingly, negotiators generally do not want to craft extensive provisions on the matter, but rather desire to create flexibility so that this can be satisfactorily addressed if and when it arises.

The two main mechanisms considered for accession of nuclear-armed states are that a nuclear-armed state would verifiably dismantle its arsenal before joining the treaty or, at the time of joining the treaty, a nuclear-armed state would be subject to a time-bound obligation to dismantle verifiably its arsenal; the obligation and the accompanying arrangements would be subject to approval by treaty members. The treaty could provide for both possibilities. Ensuring compliance with the treaty by nuclear-armed states and nuclear ally states as well could be facilitated by requiring that each state adhering to the treaty provide a declaration regarding whether it possesses nuclear weapons and whether they are located in any place under its jurisdiction or control. Such a requirement is found in the CWC.

Some attention was paid to final clauses, among them those relating to entry into force and withdrawal. Numerous states supported a clause on entry into force requiring only that a set number of states ratify the treaty, with proposed figures ranging from 25 to 80.

Concerning withdrawal, New Zealand expressed a preference for having no clause contemplating that states might withdraw, given that the treaty will set a global norm prohibiting nuclear weapons. South Africa opposed a withdrawal clause on the ground that the matter is adequately regulated by general rules of international law. They might permit withdrawal, for example, based on an unforeseeable "fundamental change of circumstances." A countervailing factor, as New Zealand recognized, is that having a withdrawal provision makes it easier for states to join a treaty.

Other states favored having a withdrawal clause subject to strict requirements, such as a lengthy period of notification and review, consideration by a meeting of states-parties, and exclusion of its exercise during armed conflict involving the withdrawing state. Brazil stated that the NPT withdrawal clause could serve as a basis to which additional criteria would be added. The NPT requires that the withdrawing state notify states-parties and the UN Security Council that it has decided extraordinary events, related to the subject matter of the treaty, have jeopardized the supreme interests of its country.

Clearly, the question of how to handle, indeed whether to permit, withdrawal would be crucial for a global treaty eliminating nuclear weapons. It perhaps is less important in the case of a treaty focused on prohibitions, given that there seems no near-term prospect of participation by nuclear-armed states. Nonetheless, it would seem best, at a minimum, to impose stringent requirements on withdrawal.11

Preamble Content

The preamble is important in a typical treaty because it provides guidance as to interpretation and application of the treaty. In the case of a nuclear weapons prohibition treaty, the preamble assumes added importance because the treaty in part is aiming to affirm and advance normative standards and, in so doing, educate the world about the imperatives of nonuse and elimination of such weapons.

Hiroshima survivor Setsuko Thurlow told ban negotiators March 27 that “no human being should ever have to experience the inhumanity and unspeakable suffering” caused by nuclear-weapons use. “We hibakusha have no doubt that this treaty can, and will, change the world,” she said. (Photo credit: Ari Beser/ICAN)From both governmental and civil society participants, there were numerous proposals on preamble content. They included calls for the preamble to refer to the humanitarian consequences of nuclear explosions; the grounding of the treaty in fundamental rules of international humanitarian law; the obligation to ensure respect for international humanitarian law; the obligation to pursue in good faith and conclude negotiations on nuclear disarmament; the role of the treaty in achieving a world free of nuclear weapons; the contribution of the treaty to the objective of general and complete disarmament; the contribution of the treaty to the three pillars of the United Nations: peace and security, human rights, and development; the role of public conscience, including the voices of the hibakusha and other victims of nuclear weapons, in banning nuclear weapons; and more.

Austria urged that the preamble reference the findings of the Oslo, Nayarit, and Vienna conferences on the humanitarian impact of nuclear weapons use, including "that impact of a nuclear weapon detonation, irrespective of the cause, would not be constrained by national borders and could have regional and even global consequences, causing destruction, death and displacement as well as profound and long-term damage to the environment, climate, human health and well-being, socioeconomic development, [and] social order and could even threaten the survival of humankind." This seems appropriate in that the negotiations have their genesis in those conferences.

Chile, Costa Rica, Cuba, Egypt, Iran, Liechtenstein, New Zealand, South Africa, Sri Lanka, Thailand, and others proposed that the preamble recognize or reflect the incompatibility of use of nuclear weapons with international humanitarian law. Citing the late Judge Christopher Weeramantry, Sri Lanka said that the "illegality of the threat or use of nuclear weapons in any circumstances could be the key underlying principle that could drive a legally binding instrument to prohibit nuclear weapons." For other states, there appears to be some reluctance to venture in this manner into contested terrain, contested above all by the nuclear-armed states, but the reasons to do so are compelling.

An affirmation of the illegality of use would reinforce the norm of nonuse of nuclear weapons. The norm arises out of a broad but not universal recognition that use of nuclear weapons is incompatible with international humanitarian law and the practice of nonuse of such weapons in war since 1945. Also, the core operative prohibitions of the treaty will apply only to states-parties. Any implication that nonparty states are permitted to use nuclear weapons must be avoided. An affirmation of illegality of use is one way of doing so.

Another important means of underlining that states outside the treaty cannot escape the fundamental prohibitions it codifies would be to include the famous Martens Clause found in international humanitarian law treaties and the Convention on Cluster Munitions. Here it would provide that, in cases not covered by the nuclear weapons prohibition treaty or by other international agreements, civilians and combatants remain under the protection and authority of the principles of international law, derived from established custom, the principles of humanity, and the dictates of public conscience.


During the first week of negotiations, diplomats and civil society were energized, even passionate, and worked constructively. A fresh wind is blowing in the stagnant nuclear disarmament sphere. All signs are that the energy will carry through into the demanding second session of negotiations. It will be needed to successfully meet the challenges not only of reflecting the results of the initiative on the humanitarian impact of nuclear weapons use, but also codifying and advancing law relating to development, possession, and use of nuclear weapons and helping shape future elimination of nuclear arsenals.


1.   UN General Assembly, "Taking Forward Multilateral Nuclear Disarmament Negotiations," A/RES/71/258, 11 January 2017. It was adopted by a vote of 130 to 37, with 15 abstentions on December 23, 2016.

2.   For statements on the positions of governments, see Reaching Critical Will, "Statements from the Nuclear Weapon Ban Treaty Negotiations," n.d., http://www.reachingcriticalwill.org/disarmament-fora/nuclear-weapon-ban/statements; United Nations, "United Nations Conference to Negotiate a Legally Binding Instrument to Prohibit Nuclear Weapons, Leading Towards Their Total Elimination," n.d., https://www.un.org/disarmament/ptnw/index.html. In some cases, diplomats made remarks not contained in the statements.

3.   UN General Assembly, "Taking Forward Multilateral Nuclear Disarmament Negotiations," A/RES/71/258, 11 January 2017.

4.   For a useful analysis of many of the issues under negotiation, see John Borrie et al., "A Prohibition on Nuclear Weapons: A Guide to the Issues," International Law and Policy Institute and the UN Institute for Disarmament Research, February 2016, http://unidir.org/files/publications/pdfs/a-prohibition-on-nuclear-weapons-a-guide-to-the-issues-en-647.pdf.

5.   A prohibition of development is not contained in the Treaty of Tlatelolco or the Treaty of Rarotonga.

6.   Treaty of Pelindaba and the Treaty on a Nuclear-Weapon-Free Zone in Central Asia.

7.   This is the approach taken by the Central Asian nuclear-weapon-free-zone treaty.

8.   See United Nations Conference to Negotiate a Legally Binding Instrument to Prohibit Nuclear Weapons, Leading Towards Their Total Elimination, "Topic 2: Core Prohibitions," A/CONF.229/2017/NGO/WP.18, March 31, 2017.

9.   See also International Association of Lawyers Against Nuclear Arms, "Selected Elements of a Treaty Prohibiting Nuclear Weapons," IALANA Discussion Paper, March 24, 2017, http://lcnp.org/pubs/2017/IALANA/IALANA%20Discussion%20Paper%201.0final.pdf.

10.   See United Nations Conference to Negotiate a Legally Binding Instrument to Prohibit Nuclear Weapons, Leading Towards Their Total Elimination, "Positive Obligations in a Treaty Prohibiting Nuclear Weapons: Stockpile Destruction, Environmental Remediation, and Victim Assistance," A/CONF.229/2017/NGO/WP.10. March 27, 2017.

11.   See United Nations Conference to Negotiate a Legally Binding Instrument to Prohibit Nuclear Weapons, Leading Towards Their Total Elimination, "Withdrawal Clauses in Arms Control Treaties: Some Reflections About a Future Treaty Prohibiting Nuclear Weapons," A/CONF.229/2017/NGO/WP.13, March 31, 2017.

Key Issues in Negotiations for a Nuclear Weapons Prohibition Treaty

Addressing Verification in the Nuclear Ban Treaty

June 2017 

By Zia Mian, Tamara Patton, and Alexander Glaser

The UN General Assembly last December called for negotiations this year to produce a "legally binding instrument to prohibit nuclear weapons, leading to their total elimination." The nuclear ban treaty talks will have to engage the issue of confirming compliance by the parties with the specific prohibitions established by such a treaty and, in addition, can establish guiding principles for the process of eliminating nuclear weapons and maintaining the resulting nuclear-weapon-free world.

Delegates at the UN conference to negotiate a nuclear weapons prohibition treaty hold opening-day talks at the United Nations in New York on March 27. (Photo credit: Tamara Patton)During the first round of treaty negotiations in March leading to the draft text presented in May, there appeared to be broad agreement among states on most of the core prohibitions but debate over a few others.1 States by and large seemed to agree on the treaty including, as basic obligations, a ban on the development, production, possession, transfer, use, and threat of use of nuclear weapons and on the provision of assistance, encouragement, and inducement for these activities. There were differences among states over whether the treaty should include measures on the elimination of existing nuclear-weapon-stockpiles or whether such measures should await later negotiations with the nine states having nuclear weapons today, who at some time may decide to join the ban treaty.2

There also were differences among states on how to treat verification. The ban treaty talks and the larger disarmament process they seek to put in place will need to consider how to assure compliance with their commitments for three classes of states: (1) established non-nuclear-weapon states that join the treaty, (2) transitional nuclear-weapon states that commit to eliminate their weapon stockpiles when joining the treaty, and (3) legacy nuclear-weapon states with latent capabilities after having joined the treaty.

As part of establishing a perspective on verification, the ban treaty process will need to make some broad choices about the eventual arrangements for a nuclear-weapon-free world, recognizing that there are many possible such end states and that some of these will be more resilient than others. This presents an opportunity to establish forward-looking guidelines on ensuring the greatest possible transparency, accountability, and irreversibility in the process for achieving and maintaining the elimination of nuclear weapons. The International Atomic Energy Agency (IAEA) can play an important part in shaping and implementing the verification process. By its statute, the IAEA is charged to further "the establishment of safeguarded worldwide disarmament…in conformity with any international agreements entered into pursuant to such policies."3

Building on the NPT

Many of the key prohibitions envisaged for the ban treaty already are captured by the nuclear Nonproliferation Treaty (NPT). Under Article II of the NPT, each non-nuclear-weapon state undertakes "not to manufacture or otherwise acquire nuclear weapons or other nuclear explosive devices; and not to seek or receive any assistance in the manufacture of nuclear weapons or other nuclear explosive devices."4 Under Article III.1, each non-nuclear-weapon state is bound to accept safeguards through IAEA monitoring and inspections "as set forth in an agreement to be negotiated and concluded with the [IAEA]…for the exclusive purpose of verification of the fulfilment of its obligations assumed under this Treaty."

There are 172 non-nuclear-weapon states with comprehensive safeguards agreements with the agency, and 124 states have in place additional protocols that require more extensive reporting by states of their nuclear activities and permit the IAEA increased rights of access to information and sites.5 Of the 130 states-participants in the negotiations, only seven do not have comprehensive IAEA safeguards agreements in force, and all but one of these have agreed to do so. This means that almost all of these 130 states already have in place verification structures that could provide assurance these states are in compliance with many of the expected core ban treaty provisions (table 1).

Further, among the 130 states seeking to agree on the ban treaty, 94 states are also members of nuclear-weapon-free-zone treaties. Each of these treaties includes an obligation, separate from that in the NPT, to conclude a safeguards agreement with the IAEA. This language varies between the zone treaties and became more precise and demanding with the most recent agreement (the 2006 Central Asian Nuclear-Weapon-Free-Zone Treaty) requiring states to conclude with the IAEA a comprehensive safeguards agreement and an additional protocol to that agreement.6 Most nuclear-weapon-free-zone treaties also have provisions, in case of compliance concerns, for special inspections that can be conducted at the request of states-parties by the IAEA or the zone’s implementation body.

This opens the way for the ban treaty to put in place a multilateral arrangement that adopts IAEA safeguards as part of its verification regime, as a parallel obligation to that of the NPT and nuclear-weapon-free-zone treaties, including provisions for special inspections. As is already the case for states that are parties to the NPT and a nuclear-weapon-free-zone treaty, one safeguards agreement with the IAEA is sufficient to satisfy multiple obligations. It also can ease concerns that a state may seek to demonstrate its commitment to nuclear disarmament by joining the ban treaty but use this as an excuse to leave the NPT and thereby end up outside a verification regime.

A U.S. delegation led by State Department official Sung Kim crosses the military demarcation line between North and South Korea May 10, 2008, carrying boxes of North Korean documents. North Korea had declared its separated plutonium inventory and provided 18,000 pages of records on the operation of its production reactor and reprocessing facility to permit verification in response to a U.S. proposal for “full access to records.” (Photo credit: Chung Sung-Jun/Getty Images)The ban treaty could adopt a simple verification obligation using language similar to that in the nuclear-weapon-free-zone treaties, while recognizing that some verification obligations already exist and more stringent verification may be necessary as nuclear-weapon states transition to join the treaty. For example, the treaty could require parties to maintain the nuclear disarmament and nonproliferation obligations they had in force as of January 1, 2017, and to accept as soon as possible the most stringent such measures available and to accept all future safeguards, monitoring, and verification obligations as agreed by the ban treaty conference of parties. This would create a stable, common verification baseline as of the start of the negotiations and a mechanism for the agreed evolution and improvement of the verification regime over time.

The final documents of the 2000 and 2010 NPT review conferences and the draft final document of the 2015 review conference each offered the same guidance on the issue of future verification in non-nuclear-weapon states and in nuclear-weapon states in the context of their nuclear disarmament: "The Conference…stresses that comprehensive safeguards and additional protocols should be universally applied once the complete elimination of nuclear weapons has been achieved."7 This guidance could be adopted by the ban treaty process.

Weapons Elimination

Because the goal of the ban treaty is to strengthen the legal and normative basis for a process leading to the elimination of nuclear weapons, an important concern will be establishing guidelines for dealing with nuclear-weapon states committing to eliminate their weapons stockpiles through the ban treaty process. The UN resolution establishing the negotiating conference highlighted that, along with the ban treaty, "additional measures, both practical and legally binding, for the irreversible, verifiable and transparent destruction of nuclear weapons would be needed in order to achieve and maintain a world without nuclear weapons."8

Rather than trying to set up specific, detailed measures to eliminate nuclear weapons, the ban treaty could simply specify that any nuclear-weapon state seeking to join the treaty must do so through an arrangement agreed with the conference of parties to the treaty. This would allow the issue to be addressed on a case-by-case basis, reflecting the particular history, circumstances, and capabilities of the state seeking to accede to the treaty. This flexibility may be necessary given the diversity in the arsenals and programs of the nine states possessing nuclear weapons today.

In principle, any nuclear-weapon state wishing to join the ban treaty could sign the treaty, declare its weapons holdings, and accept international monitoring of the process of taking its weapons off deployment, disabling them, and placing them in secure storage pending their verified elimination as part of an agreed, time-bound plan. This is the model used in the Chemical Weapons Convention (CWC), which requires that states declare their chemical weapons and "provide access to chemical weapons...for the purpose of systematic verification" along with a "general plan for destruction", stipulating that "such destruction shall begin not later than two years after this Convention enters into force for it and shall finish not later than 10 years after entry into force of this Convention."9 Following the CWC example, this plan could include destruction of delivery systems specially designed or certified by the state for nuclear weapons missions.

A state could choose to dismantle its nuclear weapons before joining the treaty and then offer up for verification its non-nuclear-weapon status, as was the case with South Africa’s accession to the NPT. This approach, however, would make the eventual verification process more difficult and time consuming and leave greater uncertainty.

In 1989, South Africa decided to terminate its nuclear weapons program. The highly enriched uranium (HEU) cores of its six existing weapons and for a seventh planned weapon were melted down, other key weapons components were destroyed or damaged so they could be not reused, and documents on weapons design and manufacturing were destroyed. In 1991, South Africa joined the NPT and signed a safeguards agreement with the IAEA. After South Africa in March 1993 revealed its nuclear weapons program, the IAEA inspections had to expand to include confirmation that the nuclear weapons, components, and related manufacturing equipment had been destroyed and that nuclear weapons laboratory and engineering facilities had been decommissioned or converted to peaceful purposes and the former weapons material accounted for.

This IAEA assessment included suggestions to South Africa about other components and information that could be destroyed and what destruction should involve.10 The IAEA recommended that "destruction" of nuclear components should be such that the "critical dimensions of destroyed components would no longer be measurable or reproducible, that the intended function would no longer be recognisable or that a destroyed item could not be reconstituted faster or more economically than it could be redesigned or rebuilt."11

In September 1993, the IAEA reported that it had "found no indication to suggest that there remain any sensitive components of the nuclear weapons programme which have not been either rendered useless or converted to commercial non-nuclear applications or peaceful nuclear usage."12 The lead IAEA inspectors concluded that

[t]he IAEA’s assessment of the complete-ness of South Africa’s inventory of nuclear facilities and materials and its assessment of the status of the former nuclear weapons programme - as in all cases where a large nuclear programme comes under safeguards - is not free from uncertainty.

In the case of South Africa, the results of extensive inspection and assessment, and the transparency and openness shown, have led to the conclusion that there were no indications to suggest that the initial inventory is incomplete or that the nuclear weapon programme was not completely terminated and dismantled.13

Only in 2010, nineteen years after South Africa’s initial report, was the IAEA able to include the country in its list of states where it could conclude "all nuclear material remained in peaceful activities."14 Olli Heinonen, a former head of the IAEA Department of Safeguards, in a study of the South African case concluded that "it is clear that the process of verification after the fact of dismantlement having taken place meant time added to the clock for the IAEA in terms of providing assurances."15

In verifying the elimination of existing nuclear weapons programs, the ban treaty process will need to address existing nuclear arsenals, which range from about 7,000 weapons each in the United States and Russia to the fissile material equivalent of perhaps 10 weapons in North Korea.16 It also will need to tackle the associated infrastructure, which for the United States and Russia produced tens of thousands of nuclear weapons over the past 70 years.17 As a first step, the process will require monitoring up to about 100 sites believed to hold nuclear weapons today (figure 1). This task could be made simpler if nuclear-weapon states were to begin a transparent monitored process of consolidating their nuclear weapons complexes to fewer sites that were configured to be accessible to international inspectors and accounting for past weapons-related activities.18

It is reasonable to assume that a South African-style verification of warhead dismantlement and accounting of fissile material production would be a much more difficult task, may take several decades to complete, and may be fraught with large uncertainties. It would be much more manageable if verification was agreed in advance and nuclear warhead dismantlement and destruction and material disposition actually observed to ensure the process met agreed standards.

In anticipation and support of these future verification efforts, both nuclear-weapon and non-nuclear-weapon states ought to pursue with a greater sense of urgency joint efforts to develop and demonstrate inspection systems for verified warhead storage and dismantlement. Equally important, nuclear-weapon states ought to begin now to document warhead assembly, refurbishment, and dismantlement activities and movements of warheads and warhead components through the weapons complex in ways that international inspectors will find credible at a later time. This includes generating and preserving appropriate records for all relevant transactions. Modern cryptographic techniques, such as blockchaining, could help demonstrate the authenticity of these records in the future.19 Although these records would not necessarily be made public now, they would help establish the provenance of treaty-accountable items and drastically simplify the verification challenges of nuclear disarmament.

Legacy Capabilities

As part of its verification of the disarmament of South Africa, the IAEA agreed with that government "to consult on future strategies for maintaining assurance that the nuclear weapons capability would not be regenerated."20 Accordingly, the IAEA took up the government’s invitation to provide the IAEA with "full access to any location or facility associated with" the former nuclear weapons program and to "grant access, on a case--by-case basis, to other locations or facilities that the IAEA may specifically wish to visit."21

The problem of legacy capabilities will be more significant for the nine current nuclear-weapon states. It will be most acute in the case of the United States and Russia, which have had the largest and most complex weapons programs by far. The scale of the challenge was captured in a 1997 National Academy of Sciences report, which assessed that

[i]f all nuclear warheads were eliminated, the current nuclear weapon states, and probably a dozen or more other countries, could in a national emergency produce a dozen simple fission weapons in as little as a few months, even if no effort had been made to maintain this capability. On the other hand, the production of a hundred lightweight thermonuclear bombs or warheads equipped with modern safety and security devices might take several years, even if special efforts had been made to maintain the capability to produce such weapons.22

The timescale and the size of reconstituted nuclear forces identified by this report depends fundamentally on the access to nuclear weapons-usable fissile material, i.e., plutonium and HEU. Therefore, the ban treaty process must consider adding, either as an immediate obligation or as a goal of the treaty process, a prohibition on the production, stockpiling, and use of nuclear weapons-usable materials for any purpose. For the existing stockpiles of fissile materials—about 1,350 tons of HEU and 510 tons of separated plutonium—the treaty could make recommendations for a framework to deal with the disposition and elimination of these materials and, for the interim period, envision their international custody (figure 2).23

Any state wishing to build or reconstitute a simple nuclear arsenal would need first to produce tens to hundreds of kilograms of plutonium or HEU, which would increase the scale of the reconstitution, its complexity, and the time required, which together increase the risk of early detection. If the elimination of nuclear weapons was accompanied by a phaseout of nuclear power, reconstitution would be made even more difficult, and its verification would be made even easier.24

Weapons-Related Research

Along with access to fissile material, research and development efforts leading to a weapons capability will be a key challenge for a legacy nuclear-weapon state seeking to reconstitute a nuclear arsenal, as it is for a would-be nuclear proliferant state today. Because the ban treaty is expected to prohibit the development of nuclear weapons, the linked issue of prohibiting weapons-related research may also be important. Notably, there is an explicit constraint on such activities for states in the African nuclear-weapon-free zone.25

The NPT and the IAEA safeguards system have grappled with this question recently in the case of Iran. The IAEA report on Iran’s nuclear program identified research and testing activities and management structures judged to have been "relevant to the development of a nuclear explosive device."26 Among other things, these activities included specific kinds of computer modeling, the development of detonators, systems for triggering high explosives, hydrodynamic experiments, and neutron initiation.

The 2017 Carnegie Endowment report "Toward a Nuclear Firewall" identified a similar set of "activities, materials, and equipment that should be inhibited because they are purely or strongly associated with nuclear weapons programs."27 The critical weapons-related activities to be prohibited included

  • milling of plutonium or uranium shells, spheres, or hemispheres;
  • neutron generators;
  • tritium technology;
  • hydrodynamic codes and experiments;
  • preparations for a nuclear test explosion, including devices using inert materials;
  • modification of a delivery vehicle to carry a nuclear warhead;
  • development of a re-entry vehicle; and
  • weaponization.

The report noted that states where there is evidence of all these R&D activities should be subject to greater monitoring than states where there are few signs. It also identified the importance of "contextual factors," such as secrecy regarding such activities, military involvement, and the absence of activities that one would expect if these activities were part of a civilian program and of states being part of international agreements, in making such a judgment. The overall framework was characterized as an assessment of a state’s nuclear activities in terms of "compatibility, cohesion, and consistency" with a peaceful or military purpose. The report concluded that, "as a general principle, activities that alone and/or in combination elicit warning that nuclear weapons are being pursued should not appear in states that have completed a nuclear disarmament process."28 The ban treaty could give guidance that all nuclear R&D activities should be able to demonstrate they meet such criteria for a peaceful purpose.

Technological and Societal Verification

The UN open-ended working group on nuclear disarmament negotiations in its 2015 report to the General Assembly helped lay the basis for the ban treaty talks and suggested some verification measures that could be part of such a treaty process, such as routine and challenge inspections, as well as measures for the use of on-site sensors, satellite photography, radionuclide sampling, and other remote sensors. The measures also include information sharing with other organizations, and citizen reporting and establishment of an international monitoring system, which includes making information available through a registry.29

Former Israeli nuclear technician Mordechai Vanunu flashes the V-for-victory sign as he leaves prison April 21, 2004, after an 18-year sentence for revealing details of Israel’s secret nuclear-weapons program. In 2005, he told Israel’s Channel 2 television that he had acted after becoming alarmed by the danger posed by Israel’s nuclear weapons program. Under a policy of “strategic ambiguity,” Israel neither confirms nor denies having the region’s only nuclear weapons. (Photo credit: Pedro Ugarte/AFP/Getty Images)Some of these measures go beyond what is part of the current IAEA safeguards system. The IAEA, however, already complements its on-site monitoring equipment and inspections with open-source information and satellite imagery as part of an "all source" approach.30 Further technology advances in the areas of commercial satellite imagery, sensor networks, and information sharing can be harnessed to verify the ban treaty and nuclear weapons elimination and sustain a nuclear weapons-free world.

Large constellations of small satellites, some of which are already being deployed, aim to provide daily coverage of the entire planet. This qualitatively new capability could be combined with the large archives of existing satellite imagery to provide a "time machine" showing what has been happening at a particular site once it has been identified as a possible site of concern. More frequent imagery, combined with improvements in machine learning techniques, could also offer improved abilities to identify such sites. New means for tracking and authenticating warheads and unattended and remote-sensor networks at weapons storage sites are possible that could lay the basis for an international monitoring system to support the disarmament process. The ban treaty could include a commitment to continue developing specific measures to strengthen the verification of elimination and a nuclear weapons-free world, similar to the process envisioned in the Comprehensive Test Ban Treaty.31

It has long been recognized that any system of nuclear verification would gain from access to information that could be provided by scientists and technicians inside nuclear programs, as well as by ordinary citizens, with regard to possible violations of a treaty.32 This would be especially important for exposing R&D activities that might be part of building or maintaining a nuclear weapons capability. Government and corporate scientists and technicians who blow the whistle and civil society groups have a long history of publicly reporting violations of national laws and international agreements. Many have paid a high price for exposing governmental or corporate secrets.

There is a limited history of individuals exposing nuclear weapons activities. The most famous example is Mordechai Vanunu, the Israeli technician jailed for 18 years for revealing details of Israel’s nuclear weapons program in 1986. At trial, Vanunu defended his actions as necessary to force Israel to acknowledge its secret weapons program and open it for inspection so that Israel could disarm.33 Among Vanunu’s defenders was the late Nobel laureate Joseph Rotblat, a Manhattan Project physicist who became a founder of the Pugwash movement of scientists against nuclear weapons. Rotblat advocated that the "right and the civic duty of the citizen" to report improper nuclear activities should be embedded in any nuclear disarmament treaty. His 1993 proposal called for this right and duty to "become part of the national codes of law in the countries party to the treaty…[and be] explicitly expressed in a specific clause of that treaty."34 The ban treaty should include such a Rotblat clause.


The inclusion of verification elements in the ban treaty is feasible and important. Most of the proposed core prohibitions are already covered in existing legal structures and associated verification mechanisms. In addition, the treaty’s verification framework will be valuable in the process leading to the elimination of nuclear weapons and may be easier to manage in key regards than arms control treaties that set numerical limits on nuclear weapons.

The ban treaty could require parties to maintain the safeguards obligations they already have in force and establish the goal of convergence in transparency through all states accepting a comprehensive safeguards agreement and an additional protocol as a verification baseline. It also could provide guidelines for the process for nuclear weapons elimination, including the need for verified declarations, warhead disabling, and monitored warhead storage pending warhead and facility dismantlement on an agreed schedule and with agreed criteria. The goal can be specified as making the disarmament process and outcome as transparent, accountable, and irreversible as possible. To facilitate future verification, nuclear-weapon states ought to begin now to document warhead assembly, refurbishment, and dismantlement activities.

The ban treaty process could consider, as an immediate obligation or as a goal of the treaty process, a prohibition on the production, stockpiling, and use of nuclear weapons-usable fissile material for any purpose. Finally, a treaty commitment to developing and accepting new verification technologies and requiring laws in states imposing obligations on all citizens to report possible prohibited activities and protecting those who do so can play an important role in verifying the ban treaty and nuclear weapons elimination and sustaining a nuclear weapons-free world.


1.   For statements from the first round of negotiations on March 27-31, 2017, see http://www.reachingcriticalwill.org/disarmament-fora/nuclear-weapon-ban/statements; https://www.un.org/disarmament/ptnw/statements.html. The draft treaty is at http://www.reachingcriticalwill.org/images/documents/Disarmament-fora/nuclear-weapon-ban/documents/CRP1.pdf.

2.   For a brief summary of the positions expressed in the first round of ban treaty discussions regarding key obligations, see Allison Pytlak, News in Brief, Nuclear Ban Daily, March 30, 2017, pp. 10-13, http://www.reachingcriticalwill.org/images/documents/Disarmament-fora/nuclear-weapon-ban/reports/NBD1.4.pdf.

3.   For an online version of the text of the Statute of the International Atomic Energy Agency (IAEA), see IAEA, Statute of the IAEA, https://www.iaea.org/about/statute (art. 3.B(1)).

4.   William C. Foster, the U.S. negotiator to the nuclear Nonproliferation Treaty (NPT), in testimony to the Senate Foreign Relations Committee said that, under NPT Article II, the construction of an experimental or prototype nuclear explosive device would be covered by the term ‘manufacture’ as would be the production of components which could only have relevance to a nuclear explosive device. Statement by ACDA Director Foster to the Senate Foreign Relations Committee: Nonproliferation Treaty, July 10, 1968, Documents on Disarmament 1968, U.S. Arms Control and Disarmament Agency, no. 52 (September 1969), pp. 498-504, http://unoda-web.s3-accelerate.amazonaws.com/wp-content/uploads/assets/publications/documents_on_disarmament/1968/DoD_1968.pdf.

5.   For a list of states with IAEA safeguards and additional protocols, see IAEA, Status List: Conclusion of Safeguards Agreements, Additional Protocols, and Small Quantities Protocols, October 7, 2016, https://www.iaea.org/sites/default/files/16/10/sg_agreements_comprehensive_status_list.pdf. See also IAEA, The Structure and Content of Agreements Between the Agency and States Required in Connection With the Treaty on the Non-Proliferation of Nuclear Weapons, INFCIRC/153 (Corrected), June 1972; IAEA, Model Additional Protocol to the Agreement(s) Between State(s) and the International Atomic Energy Agency for the Application of Safeguards, INFCIRC/540, September 1997.

6.   For an online version of the text of the Central Asian nuclear-weapon-free-zone treaty, see UN Office for Disarmament Affairs (UNODA), Treaty on a Nuclear-Weapon-Free Zone in Central Asia (CANWFZ), http://disarmament.un.org/treaties/t/canwfz/text.

7.   2000 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, Final Document, NPT/CONF.2000/28 (Parts I and II), 2000, p. 4. See 2010 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, Final Document, NPT/CONF.2010/50 (Vol. I), 2010, p. 25. For a repetition of this language, see 2015 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, Draft Final Document, NPT/CONF.2015/R.3, May 21, 2015, p. 4.

8.   UN General Assembly, Taking Forward Multilateral Nuclear Disarmament Negotiations, A/RES/71/258, January 11, 2017.

9.   For an online version of the text of the Chemical Weapons Convention, see Organisation for the Prohibition of Chemical Weapons, Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction, n.d., https://www.opcw.org/fileadmin/OPCW/CWC/CWC_en.pdf.

10.   The IAEA recommended among other things destruction of photographs and drawings which could reveal significant dimensions or the design of the nuclear material core and any components that would simplify engineering design or reveal dimensions of other sensitive components. IAEA General Conference, The Denuclearization of Africa (GC(XXXVI)/RES/577): Report by the Director General, GC(XXXVII)/1075, September 9, 1993, attach. 1, pp. 8-9.

11.   Ibid., p. 9.

12.   Ibid., p. 11.

13.   Adolf von Baeckmann, Garry Dillon, and Demetrius Perricos, Nuclear Verification in South Africa, IAEA Bulletin, No. 1 (1995), pp. 42-48.

14.   Olli Heinonen, Verifying the Dismantlement of South Africa’s Nuclear Weapons Program, in Nuclear Weapons Materials Gone Missing: What Does History Teach? ed. Henry D. Sokolski, November 2014, p. 174, https://ssi.armywarcollege.edu/pdffiles/PUB1238.pdf.

15.   Ibid.

16.   Hans M. Kristensen and Robert S. Norris, Status of World Nuclear Forces, n.d., https://fas.org/issues/nuclear-weapons/status-world-nuclear-forces (accessed March 1, 2017).

17.   Hans M. Kristensen and Robert S. Norris, Global Nuclear Weapons Inventories, 1945-2013, Bulletin of the Atomic Scientists, Vol. 69, No. 5 (2013): 75-81.

18.   International Panel on Fissile Material (IPFM), Global Fissile Material Report 2013: Increasing Transparency of Nuclear Warhead and Fissile Material Stocks as a Step Toward Disarmament, October 2013, http://ipfmlibrary.org/gfmr13.pdf.

19.   Dominic Frisby, In Proof We Trust, AEON, April 2016, https://aeon.co/essays/how-blockchain-will-revolutionise-far-more-than-money; Joon Ian Wong, Even the U.S. Military Is Looking at Blockchain Technology—To Secure Nuclear Weapons, Quartz, October 2016, https://qz.com/801640/darpa-blockchain-a-blockchain-from-guardtime-is-being-verified-by-galois-under-a-government-contract.

20.   IAEA General Conference, Denuclearization of Africa (GC(XXXVI)/RES/577), p. 4.

21.   Ibid., p. 12.

22.   Committee on International Security and Arms Control, National Academy of Sciences, The Future of U.S. Nuclear Weapons Policy (Washington, DC: National Academy Press, 1997), p. 97.

23.   The idea of international plutonium storage was extensively discussed in the 1970s and 1980s, in particular as part of the International Nuclear Fuel Cycle Evaluation. More recently, it has been proposed as a confidence-building measure for Japan’s growing stockpile of separated plutonium. Fred McGoldrick, IAEA Custody of Japanese Plutonium Stocks: Strengthening Confidence and Transparency, Arms Control Today, September 2014.

24.   Harold Feiveson et al., Unmaking the Bomb: A Fissile Material Approach to Nuclear Disarmament and Nonproliferation (Cambridge, MA: MIT Press, 2014), pp. 173-183.

25.   Article 3(a) of the African Nuclear-Weapon-Free Zone Treaty includes an undertaking [n]ot to conduct research on, develop, manufacture, stockpile or otherwise acquire, possess or have control over any nuclear explosive device by any means anywhere. For an online version of the text of the Treaty of Pelindaba, see UNODA, Treaty on a Nuclear-Weapon-Free-Zone Treaty in Central Asia (CANWFZ),  http://disarmament.un.org/treaties/t/pelindaba/text.

26.   IAEA Board of Governors, Final Assessment on Past and Present Outstanding Issues Regarding Iran’s Nuclear Programme, GOV/2015/68, December 2, 2015, p. 2.

27.   Toby Dalton et al., Toward a Nuclear Firewall: Bridging the NPT’s Three Pillars, Carnegie Endowment for International Peace, March 2017, http://carnegieendowment.org/files/CP_301_Dalton_et_al_Firewall_Final_Web.pdf.

28.   Ibid.

29.   UN General Assembly, Taking Forward Multilateral Nuclear Disarmament Negotiations: Note by the Secretary-General, A/71/371, September 1, 2016 (containing the report of the UN open-ended working group taking forward multilateral nuclear disarmament negotiations, p. 24).

30.   Matthew Ferguson and Claude Norman, All-Source Information Acquisition and Analysis in the IAEA Department of Safeguards, IAEA-CN-184/048, n.d.,  https://www.iaea.org/safeguards/symposium/2010/Documents/PapersRepository/048.pdf.

31.   For an online version of the text of the Comprehensive Test Ban Treaty, see https://www.ctbto.org/fileadmin/content/treaty/treaty_text.pdf (art. 4.a.11).

32.   IPFM, Global Fissile Material Report 2009: A Path to Nuclear Disarmament, October 2009, pp. 114-123, http://fissilematerials.org/library/gfmr09.pdf.

33.   Deborah Sontag, Israel Eases Secrecy Over Nuclear Whistle-Blower’s Trial, The New York Times, November 25, 1999.

34.   Joseph Rotblat, Societal Verification, in A Nuclear-Weapon-Free World, eds. Joseph Rotblat, Jack Steinberger, and Bhalchandra Udgaonkar (Boulder, CO: Westview Press, 1993), pp. 103-118.

Addressing Verification in the Nuclear Ban Treaty


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