June 2024
By Daryl G. Kimball

The U.S. National Nuclear Security Administration (NNSA) announced that it had successfully carried out a subcritical experiment on May 14 at an underground facility at the Nevada National Security Site.

In a May 16 statement, the NNSA said the experiment, its 34th at the former U.S. nuclear weapons testing site, provided “valuable information to…improve our modeling and simulation capability, part of the science-based [S]tockpile [S]tewardship [P]rogram.”

The agency said “the experiment performed as predicted.” It “did not form a self-sustaining, supercritical nuclear chain reaction” and therefore was “consistent with the zero-yield standard” of the Comprehensive Test Ban Treaty (CTBT).

The United States, China, and Russia continue to engage in weapons-related activities at their former nuclear testing sites. Although the treaty’s International Monitoring System is operational and more effective than originally envisioned, very low-yield nuclear test explosions such as these subcritical experiments still can be difficult to detect without on-site inspections, which will not be in place until after the treaty’s entry into force.

To address concerns about activities at former nuclear test sites, NNSA Administrator Jill Hruby announced in June 2023 that her agency is “open to working with others to develop a regime that would allow reciprocal observation with radiation detection equipment at each other’s subcritical experiments to allow confirmation that the experiment was consistent with the CTBT.”

In November 2023, Corey Hinderstein, now NNSA acting principal deputy administrator, and Marvin Adams, NNSA deputy administrator for defense programs, told Arms Control Today that the agency has been investigating technical approaches to potential confidence-building measures that could be applied to subcritical experiments without revealing classified information. Adams suggested that the most reliable strategy for independent verification of the absence of a nuclear explosion would involve measuring for the absence of a self-sustained chain reaction. That would be indicated by a very rapid drop-off in the production of neutrons and gamma rays from the experiment, he said.

To date, no technical discussions on confidence-building measures relating to subcritical experiments have been held among U.S., Chinese, and Russian officials.

June 2024
By Kelsey Davenport

States met at the International Atomic Energy Agency (IAEA) to discuss nuclear security challenges and opportunities, but an objection from Iran prevented the participants from adopting a ministerial declaration with recommendations for strengthening the nuclear security regime.

The ministerial-level International Conference on Nuclear Security (ICONS), held May 20-24 in Vienna, provided a forum for more than 130 states to discuss challenges to nuclear security, promote collaborative efforts for enhancing nuclear security, and support the IAEA’s work in this area.

In opening remarks on May 20, IAEA Director-General Rafael Mariano Grossi said the IAEA is “at the forefront of adapting nuclear security to new challenges” and referenced the role that the agency is playing in supporting nuclear security in Ukraine.

Grossi emphasized the importance of nuclear security “throughout all the steps of the nuclear fuel cycle” and described nuclear security as “part of the social contract that underpins the existence and growth of nuclear power.”

This meeting is the fourth ICONS conference and the first to conclude without a ministerial declaration. The conference focused on four themes: policy and regulations for nuclear security, technology for nuclear security detection and response, human capacity building, and cross-cutting nuclear security issues, such as the interface between security and safety.

After Iran’s objection, the co-presidents of the conference issued the draft ministerial declaration as a joint statement. Most participating states endorsed the statement in plenary remarks.

David Turk, U.S. deputy energy secretary, said the meeting comes at a time of “great change, both positive and negative” for global nuclear security efforts and described the lack of a ministerial declaration as “regrettable.” In a May 24 speech, Turk called for “renewed determination to protect nuclear facilities and material” and expressed U.S. support for the joint statement.

The joint statement calls on IAEA member states to ensure that highly enriched uranium (HEU) and separated plutonium are “appropriately secured and accounted for” and encourages states to “further minimize HEU in civilian stocks” when feasible.

The statement emphasizes that “any attacks or threats of attacks against nuclear facilities devoted to peaceful purposes may compromise nuclear security” and highlights the importance of “addressing computer security risks” to protect against cyberattacks.

The statement also recognizes the challenges and benefits posed by emerging technologies, such as artificial intelligence, and the importance of international cooperation in addressing these issues. In addition to the commitments in the joint statement, many countries used the meeting as an opportunity to announce progress on national initiatives to strengthen nuclear security and make new commitments.

Since the ICONS meeting in 2020, the United States has assisted in the disposition of 160 kilograms of weapons-usable nuclear materials in foreign countries and hosted an IAEA mission to assess the physical security of a nuclear facility, Turk said. He noted that the United States continues to contribute to the IAEA Nuclear Security Fund and reiterated U.S. support for the agency’s nuclear security work.

June 2024
By Kelsey Davenport

The head of the International Atomic Energy Agency (IAEA) traveled to Iran to discuss measures to enhance monitoring of Tehran’s nuclear program and a long-standing agency investigation into undeclared Iranian nuclear activities, but it is unclear if the trip will lead to any new cooperation.

IAEA Director-General Rafael Mariano Grossi did not announce any specific measures that Iran agreed to take, but said that Tehran showed a willingness to engage in a serious dialogue and that the two sides were discussing specific, technical steps. The deaths of Iranian President Ebrahim Raisi and Foreign Minister Hossein Amirabdollahian in a helicopter crash on May 19 further delayed engagement between Iran and the agency.

Grossi said he discussed the implementation of a joint statement of the agency and Iran in March 2023. It includes a commitment by Iran to expand voluntarily IAEA monitoring of its nuclear program and cooperate with the agency’s investigation into the presence of uranium detected at three undeclared locations. (See ACT, April 2023.)

After the March 2023 joint statement was concluded, Iran provided the IAEA with information about one of the sites where the agency was investigating the presence of undeclared uranium and allowed the agency to reinstall a limited number of surveillance cameras. But progress stalled by mid-2023.

While in Iran, Grossi tweeted that he proposed measures “for the revitalization” of the March 2023 agreement, which is “still valid.” Mohammad Eslami, head of the Atomic Energy Organization of Iran, concurred that the joint statement is a “good basis of interaction.”

Returning from Iran on May 7, Grossi told reporters that he expects to have “some concrete results soon” and that the “present state is completely unsatisfactory.”

Grossi said that it would be good to report progress ahead of the June meeting of the agency’s Board of Governors. Although there was no agreed timetable for action, he said that Amirabdolliahan had said Tehran was “ready to engage in very concrete measures.”

In the past, Iran has pledged to take action ahead of IAEA board meetings to avoid censure. If Tehran does not follow through ahead of the June meeting, it may be difficult to determine if the delay is just more stalling or if the deaths of Raisi and Amirabdollahian disrupted the agency’s engagement with Iran.

During the most recent board meeting, in March, France, Germany, and the United Kingdom said they would pursue action against Iran in June, including reporting the country to the UN Security Council, if Tehran does not provide “decisive and substantive progress” on the investigation into the presence of uranium at the two undeclared locations where the IAEA says that it still does not have sufficient information. (See ACT, April 2024.)

Grossi also suggested that his patience is waning and that he might be forced to act if Iran does not cooperate. In a May 14 interview with The Guardian, he said that, “without meaningful engagement” and being able “to see more in Iran,” the moment may come when he could not say that all of Iran’s nuclear materials are for peaceful purposes. That would be a “critical juncture” because “the international community would have to grapple with the reality that we don’t know what Iran may or may not have,” he said.

Grossi also criticized the “loose talk about nuclear weapons” in Iran and said that language “should stop.”

In a May 9 interview with Al Jazeera Mubasher, Kamal Kharrazi, an adviser to Iran’s supreme leader and a former foreign minister, said Iran has not made the decision to build nuclear weapons “but should Iran’s existence be threatened, there will be no choice but to change our military doctrine.” He specifically noted that a strike on Iran’s nuclear facilities “could lead to a change in Iran’s nuclear doctrine.” Kharrazi made similar comments on May 5.

In a May 9 press briefing, U.S. State Department spokesperson Matthew Miller called Kharrazi’s comments “irresponsible” and said the “United States will ensure one way or another that Iran will never have a nuclear weapon.

June 2024
By Daryl G. Kimball

Since Russian President Vladimir Putin launched his full-scale, illegal, and brutal assault on Ukraine in early 2022, he has issued occasional threats of nuclear weapons use against anyone who might interfere. The result is a heightened risk of nuclear war between Russia and NATO in ways not seen in the post-Cold War era.

After strong international criticism of his nuclear rhetoric in the weeks and months following the invasion, Putin dialed back his threats in 2023. But last month, he publicly authorized field exercises designed to demonstrate the potential use of substrategic nuclear weapons by Russia against NATO or Ukraine. The drills were held in Russia’s Southern Military District, which includes Russian areas adjoining Ukraine and Ukrainian territory seized by Moscow.

If nuclear weapons are used in this or any conflict between nuclear-armed adversaries, there is no guarantee that the fighting would not quickly become an all-out nuclear conflagration. As U.S. President Joe Biden warned in 2022, “I don’t think there’s any such thing as an ability to easily use a tactical nuclear weapon and not end up with Armageddon.” The Group of 20 nations also underscored the dangers in joint statements in 2022 and 2023, saying the use of nuclear weapons and threats of use are “inadmissible.”

Putin’s cronies claim that Russia’s substrategic nuclear drills are a response to statements by French President Emmanuel Macron that NATO should not rule out sending ground forces into Ukraine and by UK Foreign Minister David Cameron that Western-supplied weapons could be used by Ukraine to strike targets in Russia.

The instinct of European leaders to do more to help Ukraine is laudable, and renewed Russian attempts to use nuclear coercion to block such assistance are unsurprising, but both risk escalation that could lead to a wider European war and potential nuclear catastrophe.

Given the stakes, the international community must pursue approaches that lower tensions, increase dialogue, and resist those who threaten to break the nuclear taboo.

As U.S. and European leaders continue to supply Ukraine with the weapons it needs to repel Russia, they must calibrate carefully and coordinate their military support to avoid escalation. So far, the Biden administration has designed its military aid packages wisely and delivered increasingly advanced weapons to help Ukraine defend itself in a way that does not trigger Russian attacks on U.S. or NATO forces or territory.

U.S. and NATO leaders must continue to refrain from making rhetorical threats of nuclear retaliation, avoid provocative nuclear exercises, and rule-out mirroring counterproductive Russian moves, such as the forward deployment of Russian substrategic nuclear weapons in Belarus.

The United States could help reinforce legally binding negative security assurances for many non-nuclear-weapon states against nuclear attack by finally ratifying the protocols to three nuclear-weapon-free-zone treaties covering the South Pacific, Africa, and Central Asia that have languished in the Senate for more than a decade. Working through the Conference on Disarmament, the United States also could join with China to start negotiations on a global treaty to provide negative nuclear security assurances to all non-nuclear-weapon states.

As importantly, the world’s non-nuclear majority needs to push back harder against nuclear threats by Russia or any other state. In 2022, states-parties to the Treaty on the Prohibition of Nuclear Weapons issued an important statement noting that “any use or threat of use of nuclear weapons is a violation of international law.” They also condemned “unequivocally any and all nuclear threats, whether they be explicit or implicit and irrespective of the circumstances.” Russia was not named in the statement, but the message was clear.

One joint statement is not enough. Whenever any nuclear-armed state attempts to engage in nuclear coercion, as Russia is doing, it is in the self-interest of all states to condemn such threats and demand that offenders refrain from provocative actions.

Resuming the suspended Russian-U.S. dialogue on nuclear risk reduction and arms control is crucial to avoiding nuclear miscalculation and competition. Non-nuclear-weapon states could help by urging Moscow and Washington to meet their nuclear Nonproliferation Treaty (NPT) Article VI disarmament commitments by engaging in talks on a new nuclear arms control framework agreement before the New Strategic Arms Reduction Treaty expires in 2026.

All states concerned about nuclear escalation also could urge the five NPT nuclear-weapon states to express support for the 1973 Soviet-U.S. Agreement on the Prevention of Nuclear War, which requires that states refrain from nuclear threats and, in times of increased risk of nuclear conflict, “immediately enter into urgent consultations with each other and make every effort to avert this risk.”

So far, the 79-year-old taboo against the use of nuclear weapons has held, but the world cannot take it for granted. Tragically, the end of Russia’s war on Ukraine is nowhere in sight. To preserve and strengthen the consensus against nuclear weapons use and threats of use, we must sustain pressure against those who might try to break the nuclear taboo.