September 2026
By Amy J. Nelson 

For the first time since the early 1970s, the United States and Russia have no legally binding limits on their strategic nuclear forces. Four months before the New Strategic Arms Reduction Treaty (New START) expired, Russian President Vladimir Putin offered to observe the treaty’s central ceilings informally for one more year while the two sides worked toward a successor.¹ U.S. President Donald Trump declined. Instead, on the day the treaty lapsed—February 5, 2026—he posted on social media that “we should have our Nuclear Experts work on a new, improved, and modernized Treaty that can last long into the future.”² Trump administration officials quickly supplied the missing specifics: not a bilateral extension, but “multilateral nuclear arms control and strategic stability talks” including both Russia and China.³

It is an ambitious answer to a real problem. Judged against 80 years of arms control history, it is also the approach that is most likely to fail, for a reason that runs deeper than great-power rivalry. The conditions that make a comprehensive settlement most necessary are the same ones that make it least attainable. That paradox has governed this field since 1945, and it points to a way through.

Not a Pause

New START’s verification architecture—data exchanges, on-site inspections, and telemetry sharing—was built for a bipolar world: two comparably sized arsenals, one shared interest in predictability. That world is gone, and it went in three directions at once. Russia curtailed inspections and data declarations in 2023, well before the treaty formally lapsed. China’s arsenal has grown entirely outside any transparency regime, from roughly 260 warheads a decade ago to an estimated 620 today,⁴ with the Pentagon projecting more than 1,000 by 2030.⁵ And commercial satellite imagery and open-source analysis now do quietly what treaty inspectors used to do openly.⁶

Of the three changes, open-source visibility is the least appreciated and most consequential. Arms control’s core trade was visibility for restraint: Each side accepted intrusive disclosure because the disclosure went to a single, symmetrical adversary bound by the same limits. In a world with three main competing powers, that logic inverts. What Washington reveals to reassure Moscow is also read in Beijing, by a state bound by nothing. Verification has become a channel through which information reaches a party that never signed, and the governing question is no longer how much to disclose but to whom, about what, and in what sequence.

The institutional evidence arrived on schedule, and at the venue where the Trump administration was making its own case. Opening the nuclear Nonproliferation Treaty (NPT) 2026 Review Conference in New York in late April, U.S. Assistant Secretary of State Christopher Yeaw argued that all five nuclear-weapon states recognized under the NPT bear Article VI responsibilities, and that this was precisely why Washington has proposed multilateral strategic stability and arms control talks.⁷ China’s director-general for disarmament, Sun Xiaobo, answered that the proposal was “in essence an attempt [by the United States] to shift its special and primary responsibilities as a country with the largest nuclear arsenal onto others.” China, he said, “has no interest in them.”⁸ In May, the United States, the United Kingdom, and France issued a joint statement urging all five NPT nuclear-weapon states to engage. Russia and China were not party to that statement.⁹

What the five managed to do together is more revealing. Divided on nearly everything else, they worked in concert to strip the draft review conference outcome document of the specific commitments that would have obliged them to reduce the number and salience of their weapons.¹⁰ The conference closed May 22 without consensus—the third consecutive failure, and 16 years since states-parties last agreed on a final document.^{11 12} This outcome proved that these five states can coordinate, but what they coordinate on is the avoidance of specific obligations. None of this reflects a pause. A pause implies something that can be resumed, and the conditions under which New START was written are not returning.

Is There Anything New Here?

The instinct to go multilateral is not new, as the record shows. British Defense Secretary Des Browne proposed five-party talks at the Conference on Disarmament in Geneva in 2008, and the P5 process, a consultative mechanism initiated in 2009 to facilitate cooperation among the NPT’s five nuclear-weapon states, has met, on and off, ever since.¹³ Eighteen years in, the process has produced joint statements on strategic stability and support for the Comprehensive Test Ban Treaty.¹⁴ It has not produced a single limit on anyone’s nuclear forces. What happened in New York this year was not an aberration. It was the process working as it always has.

Alexey Arbatov, a Russian nuclear expert, laid out the structural reason for that record in June 2026: The United States, the UK, and France are allies with no interest in constraining one another, while Russia and China have voiced no mutual concern about each other’s arsenals since the late 1980s.¹⁵ Mutual deterrence and rough parity are what made the Strategic Arms Limitation Talks (SALT I) and the Intermediate-Range Nuclear Forces (INF) Treaty, both between the United States and the Soviet Union, tractable. Without them, a shared ceiling has nothing to anchor it.

The Trump administration’s declared ambition—a new treaty that would mean “taking into account for all Russian nuclear weapons, both novel and existing strategic systems, and addressing the breakout growth of Chinese nuclear weapons stockpiles”¹⁶—asks five states with five different threat perceptions to accept a single common framework. The one state whose growth supplies the rationale (China) has already declined and pointed the United States back toward Russia.

Arbatov is right, and his argument can be carried further. Parity of weapons stockpiles explains who can get to the table. It does not explain what happens once they sit down. Across negotiations—from the 1946 Baruch Plan through the 2019 Hanoi summit to the collapse of the 2015 Iran nuclear deal, formally known as the Joint Comprehensive Plan of Action (JCPOA), and the maximalist demands that followed—the variable that mattered most was not whether talks were bilateral or multilateral, nor even whether the parties held comparable arsenals; it was how each side chose to handle irreducible uncertainty about the other’s intentions and capabilities.¹⁷ States that tried to eliminate that uncertainty in one comprehensive settlement, requiring the other side to resolve every open question before any cooperation could begin, reliably failed. States that managed uncertainty incrementally, trading narrow and verifiable steps that left each side’s core deterrent intact, reliably succeeded. SALT I capped select delivery systems, not entire arsenals. The INF Treaty eliminated one symmetrically threatening class of missiles, not nuclear weapons generally. Even the JCPOA, an unusually ambitious deal, constrained Iran’s program rather than eliminating it outright, and it held as long as it did precisely because it left the harder questions of Iranian intentions unresolved rather than pretending to answer them.

The intuition to seek narrower solutions is correct. Any durable future framework must now account for more sources of uncertainty than New START ever did: Russian modernization and novel systems on one side, Chinese nuclear stockpile growth on the other. Although the diagnosis is right, the implementation repeats the nuclear arms control field’s oldest error: bundling every source of uncertainty into a single comprehensive settlement, restated for a five-party table instead of a two-party one.

A genuinely new idea follows from my forthcoming book’s central argument: that arms control has succeeded when it managed irreducible uncertainty and failed when it tried to eliminate it.¹⁸ That logic persists. In the current new treaty-thin environment, where no verification regime remains to convert disclosure into assurance, managing uncertainty means governing it directly. This is what I have called “disciplined ambiguity”—the deliberate, bounded management of uncertainty to signal intent without exposing operational detail.¹⁹ Its premise is that not all uncertainty is alike. Uncertainty about political commitments and escalation thresholds breeds alarm and forces inference under pressure. Uncertainty about operational specifics—patrol patterns, deployment configurations, and response options—complicates an adversary without obscuring intent. The discipline lies in telling the two apart: clarifying commitments while preserving indeterminacy precisely where precision would create vulnerability.

In practice, this means controlled disclosure of new systems without deployment timelines or operating parameters, reciprocal notification of major exercises and tests, and communicated red lines, identifying which actions would be treated as destabilizing. This may seem like a downshift from arms control. It is, instead, what is achievable today. It does not require five capitals to agree on a shared ceiling. Instead, disciplined ambiguity requires that each dyad of nuclear powers decides separately and sequentially what to reveal, what to withhold, and how to signal intent. It is not a substitute for agreement but a practice for the interval before one—arguably a harder discipline to sustain than signing a treaty, but one that states can begin practicing now without waiting for China to change its mind about parity.

Who Leads, and Toward What?

Who, if anyone, is positioned to lead arms control’s next era, and toward what end? The Trump administration’s messaging to date provides no answers to these questions. In July 2025, Trump himself reportedly expressed interest in maintaining only New START’s central limits; by February 2026, he had rejected that course in favor of a treaty that no one in his government could yet describe.²⁰ One senior U.S. State Department official has said that a new treaty must capture the full scope of Russian and Chinese arsenals.²¹ Another official, asked directly whether an informal understanding with Russia to hold force levels steady already existed, said only, “I know of no such agreement.”²² Trump told an interviewer in January that he would “do a deal with Russia without the Chinese,”²³ if he had to—a bilateral instinct dressed in multilateral language. When Trump and Chinese President Xi Jinping met in Beijing in May, a White House fact sheet released afterward claimed a shared commitment to denuclearizing North Korea; it said nothing about China’s own arsenal because Chinese negotiators declined to discuss it.²⁴ Washington has announced a negotiation it cannot yet describe with a partner that has not agreed to come.

That vacuum is precisely where the hardest question lives: Does the world end up with most nuclear weapons managed by a handful of strongmen rather than by institutions? In one narrow sense, this has always been the case: The authority to launch nuclear weapons everywhere rests with a small number of executives, elected or not. What is new is the source of the constraint on those executives. For five decades, it was institutional: negotiated by professionals, ratified by legislatures, verified by inspectorates. The risk now is that constraint becomes personal, negotiated leader to leader, deal to deal, with no institutional commitment or memory that survives a change of government.

A version of this scenario is already playing out. The June 2026 memorandum intended to end hostilities between the United States and Iran was negotiated bilaterally,²⁵ outside the P5+1 structure (China, France, Germany, Russia, the UK, and the United States) that produced the JCPOA, and its nuclear provisions run to a single vague paragraph with no verified baseline and no snapback mechanism comparable to the one built into the 2015 Iran nuclear deal. It postponed the nuclear question rather than answered it.²⁶ If the multilateral nuclear talks that Trump has proposed follow the same model—summit-driven, thinly staffed, dependent on the goodwill of whoever occupies the Kremlin, Zhongnanhai, and the White House—then, at a given moment, frameworks will indeed have given way to personalities. Institutions that once absorbed and outlasted individual leaders are being replaced by arrangements that will not survive a single election.

What Should Happen Instead

None of this means multilateral engagement is worthless, only that it is being asked to do the wrong job. The P5 process has an 18-year record of producing shared vocabulary and doctrinal exchange, but no numerical limits; it should be tasked with exactly that kind of norm-building, including work on crisis communication and testing moratoria, rather than the kind of treaty text that it has never been able to deliver. Alongside that process, Washington should pursue narrow, sequenced, bilateral tracks. With Moscow, the priority should be an informal understanding to hold deployed strategic force levels steady while negotiators work toward a successor arrangement, paired with reciprocal transparency on nonstrategic nuclear weapons, long-range conventional strike systems, and novel strategic capabilities such as nuclear-powered cruise missiles and undersea autonomous systems.

With Beijing, the emphasis should remain on risk reduction rather than parity. This approach would include advance notification of ballistic missile launches and major strategic exercises; protocols governing dual-capable missile operations; exchanges on launch-on-warning and command-and-control practices; crisis communication procedures; and transparency measures regarding the expansion of China’s missile silo fields. Both tracks should apply the incremental logic to which my research points: narrow, verifiable, sequenced steps focused on the capabilities most likely to lead to miscalculation, rather than comprehensive settlements that ask each side to resolve every outstanding issue before either side gains anything.

Trump is right that the New START era cannot simply be extended by another five years; the treaty itself forecloses that option, and the strategic environment for which it was designed no longer exists. He is also right that China’s arsenal cannot be indefinitely excluded from any conversation about strategic stability, but recognizing the problem is not equivalent to identifying the solution. The solution on offer, a single comprehensive multilateral treaty, repeats the very error that has frustrated most major arms control initiatives since 1945. A framework rebuilt instead on incremental, disciplined management of uncertainty, pursued through parallel bilateral channels rather than all-or-nothing negotiation, has a far stronger historical record.

Whether this administration or the next chooses the harder and less photogenic path will determine whether the coming years mark the start of a new arms control era or simply the interval between frameworks, filled, as such intervals always are, with force and the private judgment of whoever holds the launch codes.

ENDNOTES

1. Vladimir Putin, “Meeting with permanent members of the Security Council,” press release, September 22, 2025.

2. Donald Trump, “The United States is the most powerful Country in the World. I completely rebuilt its Military in my First Term,” Truth Social, February 5, 2026.

3. Congressional Research Service, “U.S.-Russian Nuclear Arms Control: Overview and Potential Considerations for Congress,” February 26, 2026.

4. Hans M. Kristensen, Matt Korda, Eliana Johns, and Mackenzie Knight-Boyle, “Chinese nuclear weapons, 2026,” Bulletin of the Atomic Scientists, Vol. 82, No. 4 (2026), pp. 293-322.

5. U.S. Department of Defense, “Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China,” December 23, 2025.

6. Hans M. Kristensen, and Matt Korda, “China Is Building A Second Nuclear Missile Silo Field,” Federation of American Scientists, July 26, 2021.

7. Christopher Yeaw, “Statement by the United States to the NPT Review Conference,” U.S. Mission to International Organizations in Geneva, April 29, 2026.

8. Sun Xiaobo, “Statement by Sun Xiaobo, Director-General of the Department of Arms Control of the Foreign Ministry of China at the General Debate of the Eleventh Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT),”Ministry of Foreign Affairs of the People’s Republic of China, April 29, 2026.

9. “P3 Joint Statement for Main Committee I 2026 Review Conference of Treaty on the Non-Proliferation of Nuclear Weapons,” Permanent representation of France to the Conference on Disarmament, May 1, 2026.

10. Libby Flatoff, and Daryl G. Kimball, “2026 NPT Review Conference Stymied by Disputes,” Arms Control Today, Vol. 56 (June 2026).

11. United Nations, “Review Conference Ends without Consensus Outcome amid Rising Nuclear Risks,” meetings coverage, May 22, 2026.

12. United Nations, “(Informal Consultations) 2026 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons,” March 3, 2026.

13. Maximilian Hoell, and Andreas Persbo, “Overcoming disunity: Reinvigorating the P5 Process a decade on,” report, European Leadership Network, July 30, 2020.

14. Arms Control Association, “P5 Reiterate Commitment to CTBT,” July 1, 2011.

15. Alexey Arbatov, “The Puzzle of Multilateral Arms Control,” Arms Control Today, Vol. 56 (June 2026).

16. Thomas G. DiNanno, “Statement to the Conference on Disarmament,” U.S. Department of State, February 6, 2026.

17. Amy J. Nelson, The Arms Control Paradox (Stanford University Press, 2026).

18. Ibid.

19. Amy J. Nelson, “After New START: The Case for Disciplined Ambiguity,” New America, February 23, 2026.

20. Trump, “The United States is the most powerful Country in the World.”

21. Olivia Le Poidevin, “US meeting Russian and Chinese delegations for nuclear arms control talks, official says,” Reuters, February 24, 2026.

22. Alex Raufoglu, “New START: No ‘Gentleman’s Agreement’ Between US, Russia On Expired Nuclear Treaty,” Radio Free Europe/Radio Liberty, February 17, 2026.

23. Donald Trump, “Two Hours, Scores of Questions, 23,000 Words: Our Interview With President Trump,” interview by Zolan Kanno-Youngs, Tyler Pager, Katie Rogers, and David E. Sanger, The New York Times, January 11, 2026.

24. The White House, “Fact Sheet: President Donald J. Trump Secures Historic Deals with China, Delivering for American Workers, Farmers, and Industry,” May 17, 2026.

25. Abigail Williams, “Text of the Iran-U.S. memorandum of understanding,” NBC News, June 17, 2026.

26.  Amy J. Nelson, “What the Iran MOU Gets Right, Gets Wrong, and Leaves Unresolved,” New America, June 25, 2026.

September 2026
By Zohaib Altaf

In April 2026, the U.S. Air Force paired three nuclear energy reactor developers with Buckley Space Force Base in Colorado, Malmstrom Air Force Base in Montana, and Joint Base San Antonio in Texas. The projects remain subject to siting, environmental, licensing, and contracting decisions, but the service expects deployment by 2030 or earlier. A separate Air Force pilot project at Eielson Air Force Base in Alaska is also advancing under a commercial ownership model.¹ Military microreactors have moved beyond studies and concept papers. They now have prospective sites, vendors, and target dates.

The broader policy is even more ambitious. A May 2025 executive order directed the Defense Department, acting through the Army, to establish a formal program for nuclear power both at permanent military installations and in support of forces and weapon platforms during military operations. Separately, it required the Army to begin operating an Army-regulated reactor at a domestic base by September 30, 2028. The Army’s Janus Program is intended to supply power to installations and mission-critical systems including communications networks, weapons systems, and command nodes. On August 26, the army announced the selection of five nuclear energy vendors and five initial installations under the Janus program, with up to $2.2 billion mile-stone based government funding over fiscal year 2027-2031. The prototypes will be contractor- owned and operated and the army expects more than 20 microreactors across military installations supported by the government and private investment.² Project Pele, the Pentagon’s transportable microreactor prototype, is designed to generate at least 1.5-megawatts and received its full core of high-assay low-enriched uranium fuel in late 2025.³

None of these programs is a nuclear weapon project, and the reactors now being considered for U.S. bases are not forward-deployed battlefield systems. Their immediate purpose is energy resilience. Yet the distinction between an ordinary power plant and military capability begins to narrow when a reactor supplies mission-critical communications, sensors, command systems, or weapons infrastructure. If other states follow the U.S. lead, a familiar piece of military infrastructure may become a nuclear site as well.

The case for microreactors is credible. So is the need to govern them before deployment becomes routine. Existing safeguards, nuclear security rules, and the law of armed conflict address parts of the problem, but they were developed around civilian power, naval propulsion, and large nuclear facilities. They do not map neatly onto small, land-based reactors that may be commercially operated, use fuel enriched to higher levels than conventional power-reactor fuel, connect to military networks, and face attack in wartime. The answer is not a ban; it is a set of rules that preserves the operational value of these systems without allowing military status to become a blanket justification for secrecy.

From Energy Resilience to Military Dependence

The military demand is easy to understand. The Pentagon’s 2023 Operational Energy Strategy warns that the U.S. homeland can no longer be treated as a sanctuary and that logistics will be contested. Fuel depots, ports, pipelines, power grids, and convoys are vulnerable to long-range strikes, cyber operations, and supply disruptions.⁴ At the same time, radar, data processing, air defense, electronic warfare, and prospective directed-energy systems are increasing the demand for reliable electricity.

Microreactors offer steady power without daily fuel deliveries. Many designs are factory fabricated, can operate independently of a large grid, and are intended to run for years before refueling. Project Pele, for example, is designed to fit into four standard shipping containers and generate at least 1.5 megawatts of electricity for up to three years. Its demonstration at Idaho National Laboratory is meant to test whether a reactor can be assembled, operated, shut down, and moved safely.⁵ Fixed reactors under the Air Force’s installation program follow a different model: Commercial firms may build, own, operate, and decommission them while selling power to the military base.

These differences are not administrative detail. A commercially owned reactor, licensed by a civilian regulator and supplying a domestic military base through a microgrid, presents one governance problem. An Army-regulated reactor assigned to operational energy and integrated with military systems presents another. A transportable reactor sent abroad would mean additional complications, including host-state consent, nuclear transport, emergency response, and wartime protection. Public policy still tends to group all three of these reactors under the single label of “military microreactor.”

The Safeguards Question, Properly Framed

The safeguards issue needs precision. The five nuclear-weapon states recognized by the nuclear Nonproliferation Treaty (NPT), including the United States, have voluntary-offer agreements with the International Atomic Energy Agency (IAEA). Non-nuclear-weapon states-parties to the treaty generally have comprehensive agreements requiring IAEA safeguards on nuclear materials used in peaceful nuclear activities.⁶ Paragraph 14 of the IAEA’s model comprehensive safeguards agreement allows a non-nuclear weapon state to seek temporary non-application of safeguards to nuclear material used in a non-explosive military activity. Because the United States operates under a voluntary-offer agreement, its current reactor projects do not trigger this procedure. The potential verification gap would arise if a non-nuclear-weapon state developed or imported a military reactor and sought to remove its fuel from safeguards under paragraph 14.

Paragraph 14 of INFCIRC/153, the standard blueprint for an IAEA safeguards agreement, provides a procedure for such a case. A state is required to inform the IAEA of the activity, affirm that the material will not be used to produce a nuclear weapon or other nuclear explosive device, and conclude an arrangement defining the period or circumstances in which safeguards will not apply. The arrangement requires approval by the IAEA Board of Governors, and safeguards must resume when the material returns to peaceful use.⁷

Military use does not automatically require non-application of safeguards. A state may leave the material under safeguards. For a fixed land-based reactor with sealed fuel and a known location, continued safeguards may be far more practical than for a submarine whose movements, design, and operating schedule are classified. This should be the starting presumption. A state seeking a paragraph-14 arrangement for a land-based reactor should have to identify the specific operational information that ordinary safeguards would expose and why managed access or safeguards by design cannot protect it.

The IAEA’s negotiations with Australia over naval nuclear propulsion, under a deal in which the United Kingdom and the United States plan to supply Australia with nuclear-powered submarines, provide a useful, although incomplete, experience. As of November 2025, the agency and Australia were still discussing advance notification, reporting, verification before material entered a paragraph-14 arrangement, voluntary transparency during the excluded period, and the point at which safeguards would resume.⁸ Land-based reactors should not simply inherit a naval exception. Their fixed location and different operating models may permit stronger verification.

Fuel makes the question more consequential. High-assay low-enriched uranium (HALEU) contains more than 5 percent but less than 20 percent uranium-235. It is not highly enriched or weapons-grade uranium, but less additional enrichment work is required to reach weapons-grade levels than from the fuel used in most commercial reactors. Many advanced reactor designs use HALEU to obtain smaller cores and longer operating cycles; Project Pele’s environmental impact statement analyzed a core containing up to 400 kilograms of HALEU in tri-structural isotropic (TRISO) fuel.⁹ Wider use would create larger inventories moving through enrichment, fabrication, transport, military, and contractor-controlled facilities.

Safeguards are only part of the gap. The Convention on Nuclear Safety applies to land-based civil nuclear power plants. The amended Convention on the Physical Protection of Nuclear Material covers material and facilities used for peaceful purposes and expressly excludes nuclear material used or retained for military purposes and facilities containing such material.¹⁰ National regulation and IAEA guidance can still provide rigorous protection, but international assurance will depend heavily on how each state classifies the reactor. A system should not lose transparency, peer review, or security discipline merely because its electricity serves a defense mission.

A Nuclear Site in the Targeting Process

Wartime status is the second major problem. Article 56 of Additional Protocol I gives special protection to dams, dykes, and nuclear electrical generating stations when an attack may release dangerous forces and cause severe civilian losses. For a nuclear station, the protection may cease only if it supplies electricity in regular, significant, and direct support of military operations and an attack is the only feasible way to end that support. Even then, the protocol requires all practical precautions to avoid releasing dangerous forces.¹¹

The provision leaves difficult questions for microreactors. Its text contains no generating-capacity threshold, for instance, but a small, sealed reactor may not resemble the large station the negotiators had in mind. A fixed reactor serving an entire base could fit the ordinary meaning more readily than a transportable unit attached to a radar or command post. Mixed civilian and military loads would further complicate the assessment.

Article 56 also is not the whole law. It binds states-parties to Additional Protocol I; the United States is not a state-party and does not accept the article’s special protection as customary international law. The U.S. position is that such installations may be attacked if they are military objectives, subject to distinction, proportionality, and precautions. The risk that an attack could release radiation or radioactive material and cause severe civilian harm would weigh heavily in those assessments.¹² Any international policy must acknowledge this legal divergence rather than present Article 56 as a universal prohibition.

Reactor design can reduce the expected consequences of attack. The use of TRISO fuel, an actual passive shutdown or the capacity for a passive shutdown, underground cabling, and physical separation may all limit risk, but they do not settle target status. An attacker might strike the substation, control link, cooling equipment, or supported military system instead of the reactor vessel. Damage could still cause radioactive release, interrupt monitoring, force evacuation, or create uncertainty about the reactor’s condition. Even when civilian harm is limited, reports of a strike on “nuclear infrastructure” may generate political pressure and escalation before reliable technical information is available.

Rules Before Reactors Become Routine

Four measures would address the most immediate risks without blocking microreactor deployment. First, states should publish a basic classification for every military reactor program: fixed or transportable; domestic installation or operational use; civilian-licensed or military-regulated; government- or contractor-operated; fuel type and enrichment band; and whether the reactor is intended to supply civilian loads, general base power, or specified mission systems. Exact vulnerabilities need not be public, but the regulatory authority and emergency responsibilities should be.

Second, the IAEA Board of Governors should commission a technical study of land-based reactors used in non-explosive military activities. The study should establish a presumption of continued safeguards for fixed reactors in non-nuclear-weapon states. Where paragraph 14 is genuinely necessary, arrangements should be material-specific and define entry and exit points, duration, reporting, reapplication of safeguards, and verification measures that protect classified information while maintaining confidence against diversion. The same work should develop safeguards-by-design guidance for sealed cores, remote monitoring, and long-life fuel.

Third, supplier states should make HALEU transfers for military reactors conditional on cradle-to-grave material accountancy, appropriate physical protection, prior consent for retransfers or changes in use, and credible plans for spent fuel return or disposition. Confidential reporting to the IAEA can protect commercially sensitive data. “National security” is not an adequate accounting category.

Fourth, siting and system design should anticipate war, not only accidents. When feasible, reactors should be physically separated from high-value command and weapons systems, and microgrids should permit military loads to be isolated without attacking the reactor. Reactor control and safety systems should be segregated from operational command networks, with independent shutdown and authenticated radiological reporting. Additional Protocol I already requires its parties to avoid locating military objectives near protected works where feasible and to take precautions for civilians under their control.¹³

Crisis communication completes the package. States operating reactors near potential conflict zones should establish channels for reporting shutdowns, attacks, cyber incidents, and radiation readings to the IAEA, host authorities, and adversaries where appropriate. India and Pakistan’s 1988 agreement prohibiting attacks on each other’s nuclear installations shows that rivals can exchange protected site information through confidential channels. They carried out their annual exchange again January 1, 2026.¹⁴ The agreement cannot simply be copied for every region, and states will hesitate to disclose military locations. It nevertheless offers a precedent for bounded notification without public exposure.

An Early Choice

Military microreactors could improve resilience, reduce dependence on vulnerable fuel deliveries, and support remote operations. Their benefits should not be dismissed because nuclear technology is involved. Nor should their small size obscure the institutional change they introduce. A base reactor can sit simultaneously inside an energy system, a nuclear fuel cycle, a commercial contract, and a military target complex.

Governments still have time to decide how those roles will be separated and supervised. The United States can set the first useful precedent by explaining which of its programs will be civilian-licensed, which will be Army-regulated, how fuel will be accounted for, and how reactor sites will be protected during conflict. The IAEA can begin the harder work before a non-nuclear-weapon state requests a paragraph-14 arrangement for a land-based military reactor.

Regulation will become more difficult once reactors are installed, supply contracts are locked in, and militaries depend on them for critical missions. The responsible course is neither prohibition nor silence. It is to establish safeguards, disclosure requirements, design standards, and crisis-management protocols while the technology is still taking shape.

ENDNOTES

1. U.S. Department of the Air Force, “DAF announces next steps in Advanced Nuclear Power for Installations initiative,” April 22, 2026; U.S. Space Force, “Buckley SFB, Malmstrom AFB selected for Advanced Nuclear Power for Installations program,” April 8, 2026; Air Force Civil Engineer Center, “DAF ignites energy innovation with microreactor pilot at Eielson AFB,” September 11, 2025.

2. U.S. Army Communication and Outreach Office, “Army Selects Vendors, Sites for Nuclear Microreactors,” August 27, 2026.

3. U.S. President Donald Trump, Executive Order 14299: “Deploying Advanced Nuclear Reactor Technologies for National Security,” May 23, 2025, Sec. 3; U.S. Army, “The Janus Program: Fueling the Army’s future with resilient, on-demand nuclear energy,” October 14, 2025; Idaho National Laboratory, “INL advances Department of War’s Project Pele demonstration microreactor with first TRISO fuel delivery,” December 2, 2025.

4. U.S. Department of Defense, “Department of Defense Operational Energy Strategy,” May 2023, pp. 1-3.

5. U.S. Department of Defense, “DoD Breaks Ground on Project Pele: A Mobile Nuclear Reactor for Energy Resiliency,” September 24, 2024; BWX Technologies, “Project Pele Begins Taking Shape With Start of Core Manufacturing,” July 24, 2025.

6. International Atomic Energy Agency, “Safeguards agreements,” accessed August 22, 2026.

7. Laura Rockwood, “The Legal Framework for IAEA Safeguards,” IAEA, 2013, p. 12; IAEA, “IAEA Safeguards Glossary,” 2022, p. 22.

8. IAEA Board of Governors, “Naval nuclear propulsion: Australia,” report by the director-general, GOV/INF/2025/12, November 12, 2025, pp. 3-5.

9. U.S. Department of Energy, “What Is High-Assay Low-Enriched Uranium (HALEU)?” December 3, 2024; National Academies of Sciences, Engineering, and Medicine, “Merits and Viability of Different Nuclear Fuel Cycles and Technology Options and the Waste Aspects of Advanced Nuclear Reactors,” 2023, pp. 181-182; U.S. Department of Energy, “Final Environmental Impact Statement for Construction and Demonstration of a Prototype Mobile Microreactor: Environmental Impact Statement,” February 2022, pp. S-9 to S-10.

10. IAEA, “Convention on Nuclear Safety,” July 5, 1994, p. 2; IAEA, “Amendment to the Convention on the Physical Protection of Nuclear Material,” p. 3, July 8, 2005.

11. International Committee of the Red Cross, “Protocol Additional to the Geneva Conventions of August 12, 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I),” June 8, 1977.

12. U.S. Department of Defense, “Law of War Manual,” July 2023, pp. 278-279; Office of the General Counsel, U.S. Department of Defense, “Official Treaty Documents Related to the Law of War,” accessed August 22, 2026.

13. International Committee of the Red Cross, Additional Protocol I, articles 56-58; Vasiliki Tafili “New CRP: Enhancing Computer Security of Small Modular Reactors and Microreactors,” IAEA Department of Nuclear Safety and Security, March 4, 2024.

14. Indian Ministry of External Affairs, “Agreement on the Prohibition of Attack Against Nuclear Installations and Facilities Between the Republic of India and the Islamic Republic of Pakistan, December 31, 1988; Indian Ministry of External Affairs, “India and Pakistan exchange list of Nuclear Installations,” January 1, 2026.

September 2026
By Magnus Öberg and Siri Jansson

Since 1817, world leaders have negotiated at least 129 arms control agreements regulating all weapons categories, including weapons of mass destruction and conventional weapons. These agreements all exist on paper and online but not in a form that is easily accessible or usable by scholars, policymakers, or anyone else who wants to examine the details in a broad context—until now.

The Alva Myrdal Centre (AMC) for Arms Control at Uppsala University in Sweden recently completed construction of the AMC Data platform, a new online database that aims to provide a comprehensive and user-friendly reference source for research and education on the complicated topic of arms control agreements.¹ The platform is built on an underlying database covering 129 arms control agreements between 1817 and 2025.

The data platform provides structured and easily accessible information about each agreement, presented in text, images, and through interactive visualization tools. Clear and comparable summaries cover basic information on each treaty catalogued, such as key dates of signature and entry into force, details on which states have signed and ratified each agreement, as well as information on which weapons or facilities are affected by the agreement and which stages of the weapons life cycle are regulated.

AMC Data also provides information on verification processes and the organizations responsible for implementing each agreement. The platform offers access to the full texts of all agreements, along with tools for visualizing and comparing states-parties and agreement contents in graphs and tables. Finally, the platform provides a series of data sets for statistical analysis.

The platform is organized around a series of typologies and conceptualizations that make agreements readily comparable with respect to various dimensions, including bans and restrictions over the life cycle of weapons systems from development to disposal, their consultation and compliance mechanisms, and relevant agreement associations. The hope is that systematizing information about the agreements and making it easily accessible will spur increased interest in comparing agreements and their evolution over time, inviting people to ask questions about what different agreements regulate—when they entered into force, how they regulate compliance—and to investigate differences over time and across nuclear and non-nuclear agreements.

The platform should be useful as a go-to reference for quick facts about the agreements, as it is to the authors’ knowledge,—the most comprehensive and systematic overview of arms control agreements available anywhere. It should serve the needs of researchers, students, and practitioners alike, and, with its companion database and data sets, provide answers and inspire new questions.

Compared to existing resources, AMC Data provides a wider range of information on a larger scope of arms control agreements than anything previously available, and it does so in a way that makes all 129 agreements over a 200-plus-year period systematically comparable at a glance. In contrast to key sources such as the UN Office for Disarmament Affairs (UNODA) Treaty Collection, the UNODA Treaty Database, the Nuclear Threat Initiative Education Center, and Arms Control Association treaty “at a glance” backgrounders, AMC Data covers a larger number of agreements and benefits from an integrated comparative framework based on its underlying data sets.

The underlying database and downloadable data sets also contribute as a resource for research in and of themselves. Previous data sets on arms control agreement parties and content are limited in scope and detail and, importantly, are not always freely available.

Contents and Structure

AMC Data is organized around four main components. First, the “AMC agreement profiles” section provides concise, systematic summaries of every arms control agreement included in the database. Written in a standardized format, each profile presents key information on agreement obligations, verification design, agreement associations, and state participation, alongside essential facts and links to the full agreement text.

Second, the platform includes three interactive data visualizers. The “agreement parties visualizer” generates timelines illustrating state actions to sign, ratify, accede to, or withdraw from arms control agreements over time. The “weapon-specific obligations visualizer” enables users to explore and compare the weapons and related objects that are prohibited or restricted by different agreements across the various stages of the weapons life cycle. Finally, the “control system catalogue” provides a searchable overview of the consultation, demonstrated compliance, and verified compliance mechanisms established by each agreement, allowing users to compare implementation and verification across agreements.

Finally, the platform includes the “AMC data portal,” which provides free access to AMC data sets and their accompanying codebooks for research and statistical analysis. Users can also download the digital version of the AMC Encyclopedia of Arms Control,² which compiles all agreement profiles into a single volume with additional visual features, including a historical timeline, to provide a more engaging reading experience.

The AMC Agreement Data Sets

The platform is built on seven interconnected data sets that systematically capture the content of arms control agreements and states’ participation in them. The “agreement dataset” records core information for each agreement, including key dates, participating states, and weapons regulated. The “weapon-specific obligations dataset” shifts the unit of analysis from agreements to individual obligations, enabling comparisons of how approximately 300 weapons or related materials are regulated across different stages of the weapons life cycle, from development and production to use and destruction. Three additional data sets focus on agreement design by documenting consultation mechanisms, demonstrated compliance mechanisms (such as reporting requirements), and verified compliance mechanisms, including how verification procedures are initiated and what forms of inspection or access they authorize. The “agreement associations dataset” records organizations responsible for treaty implementation, while the “agreement parties dataset” tracks state actions to sign, ratify, or withdraw from agreements over time.

The data sets were compiled by coding official agreement texts using a standardized codebook and by drawing on major international treaty collections. Although considerable effort was made to compile a comprehensive list of agreements, some limitations remain. Coverage is strongest for 20th-century multilateral agreements, while historical agreements, unilateral declarations, and less prominent regional or bilateral arrangements are more likely to be incomplete due to limited historical documentation and challenges in identifying all eligible agreements.

The Data and Its Uses

One important use of the AMC data is mapping trends and analyzing patterns in arms control agreements. The data can be used to analyze how any set of country characteristics, geopolitical alignments, or other attributes relates to state commitments or any other aspect of arms control agreements such as verification mechanisms or agreement associations. The possibilities are almost endless. Figure 1 shows trends in states’ commitments to arms control agreements across time and plots it against a geopolitical shift and global arms expenditures, thus illustrating how these shifts and trends relate to each other. State commitment encompasses all actions by which a country expresses its consent to be bound by an agreement, including ratification, accession, approval, acceptance, succession, consent to be bound, and participation. The dynamics changed with the end of the Cold War (a period indicated by the shaded section of the graph) and, as military spending went down, commitments to arms control agreements expanded dramatically across categories. The 1990s stand out as the decade with the highest number of agreements adopted and also as the decade with the greatest number of actions to commit to an agreement, especially in the area of conventional weapons, with important agreements such as the Treaty on Conventional Armed Forces in Europe.

A second purpose of the data portal is to provide structured, accessible, and comparable information at a user’s fingertips. It allows for easy exploration and comparisons of structure and details across a very large number of arms control agreements. For example, users interested in what a specific agreement regulates, or which agreements regulate a specific weapons type, have all the information readily available in the “weapon-specific obligations visualizer”—for any arms control agreement since 1817. By means of the visualizer, a user can easily find out what weapon or related material is regulated, how it is regulated, and what paragraph in the original agreement lays this out. The data portal also provides the original agreement. The same visualizer allows a user to obtain parallel charts for all the seven agreements regulating fissile materials for easy comparison, or all agreements regulating any one of the 300 types of weapons and related materials regulated in any agreement. This is just one example how researchers can access, compare, and visualize information about arms control agreements.

In sum, the data platform provides detailed and systematic information on 129 arms control agreements, many of them historical and less well known. Whether a user is just browsing the agreements, comparing and studying them in detail, or analyzing them statistically, the data can contribute to new insights and ideas for future arms control efforts. The data could be used to analyze how different verification mechanisms affect the likelihood of a treaty being adopted, which in turn might provide useful for thinking about how to design new agreements. It can also be used to understand what drives the type of inspections used in arms control agreements,³ or to analyze verification issues beyond traditional arms control, such as verification regimes for artificial intelligence governance.⁴ Finally, the online data platform is an ongoing project that will expand over time. In the near future, data on nuclear arms control negotiations will be added. This action will make the tool useful for analyzing the negotiating process and what conditions facilitate successful or failed negotiations.

ENDNOTES

1. See https://amcdata.uu.se/en.

2. Siri Jansson, Tereza Heiligová, Robertas Skipitis, and Magnus Öberg, The AMC Encyclopedia of Arms Control Agreements, Alva Myrdal Centre for Nuclear Disarmament, Uppsala University, 2026.

3. Philip Chennery, Yerdaulet Rakhmatulla, Joel Christoph and Joon Baek, “Who Watches? Inspector Models in Arms Control and Lessons for AI Oversight,” Alva Myrdal Centre for Nuclear Disarmament, Uppsala University, April 2026.

4. Andrew Ayobami, “Nuclear Governance Architecture and Its Limits for AI Verification,” SSRN, May 16, 2026.

September 2026
By David E. Hoffman

During the Cold War, arms control negotiations were awfully boring. The jousting and talking was exhausting and took years to achieve results. An exception was the summit between U.S. President Ronald Reagan and Soviet leader Mikhail Gorbachev in Reykjavik, Iceland, over the weekend of Oct. 11-12, 1986. This was the most dramatic and consequential discussion of nuclear danger since the 1962 Cuban missile crisis. Isolated at the Hofdi House on the barren North Atlantic coast, Reagan and Gorbachev came very close to an agreement to eliminate all nuclear weapons. The two leaders failed to do so in the end because of Reagan’s insistence on pursuing his dream of missile defense, the Strategic Defense Initiative (SDI). But they set the stage for real progress in the years that followed when the nuclear stockpiles were sharply reduced, making the world safer.

To make a movie about Reykjavik would seem to require nothing more than embracing the history as it unfolded. The transcripts and documents have been declassified, showing that Reykjavik was a summit of high political stakes, yet was also very personal. Director Michael Russell Gunn’s new film about Reykjavik, “The Brink of War,” nicely frames the mood in the first moments with a lonely Reagan, played by Jeff Daniels, staring out at a roiling sea and distant lightning.

This film goes right to the heart of why Reykjavik was a seminal event. Reagan and Gorbachev, from radically different political systems and for quite different reasons, reached the same conclusion. Over and over again during the Cold War, technology ramped up the danger. It took people who recoiled from the balance of terror to curtail the arms race. Reagan and Gorbachev found the political willpower and courage to do so—or at least to try on a fateful Sunday afternoon.

“Nuclear. Zero,” insists a stern Gorbachev (Jared Harris).

“You want to destroy every single nuclear weapon on Earth?” asks an incredulous Reagan. “Gone. Taken out of the silo, off the sub, out of the bomber, dismantled, junked, warheads spun down. In just ten years?”

“Well, then let’s do it!” responds Secretary of State George P. Shultz (J.K. Simmons), in a pivotal moment that is true to the record.

Much retelling of the Cold War is colored by knee-jerk American triumphalism—that Reagan pushed the Soviet Union into the dustbin of history. But at Reykjavik, Gunn shows that it was Gorbachev, not Reagan, who first broached radical arms reductions. Reagan could not believe what he was hearing, and he was not short of enthusiasm. “I’m saying why don’t we get rid of all of them?” he tells Gorbachev.

When the two leaders later get stuck in disagreement over missile defense, Reagan makes a guileless offer to share SDI with the Soviet Union. In what is perhaps the strongest performance of the film, Gorbachev responds with a fiery and humiliating tirade, pointing out that the United States would not share ordinary dairy equipment with the Soviet Union, so how could he take the offer seriously?

Harris deftly portrays a Gorbachev burdened by over-militarization at home, eager to get on with his political and economic openings of glasnost and perestroika, and accompanied by an enchanting Raisa Gorbacheva (Branka Katic). Reagan comes across as eager to leverage his military buildup into a legacy-defining deal; Nancy Reagan (Hope Davis) remained in Washington. Regrettably, the film does not explore the fascinating backstory of Reagan’s nuclear abolitionism, which had been largely hidden from public view until Reykjavik.

Gunn has cleverly centered the entire film on the actual Hofdi House location and eschewed the submarines and missiles that are seen in many Cold War movies. He has painlessly fiddled with the sequence of the summit events. When he hews to the history, he has a gripping tale. He did not need to weigh it down with so many cliches. “Trust, but verify,” the favorite Reagan saying, is repeated often. “Tear down this wall” pops up—although Reagan did not actually say it until the next year—and the Soviets are reminded numerous times that they have bread lines. Reagan gives a series of anti-communist mini sermons that seem discordant, even for him.

Gunn also attempts to crank up the tension from the very beginning with the idea that the superpowers were on the “brink of war.” Shultz warns the president, “You said you didn’t want to be seen as a warmonger. If we fail here, there’s going to be a war; after this war there’ll be nothing left on God’s green Earth but smoldering, irradiated, lifeless rock. Is that what you want?” This was hardly the case; tensions were much higher in the war scare of 1983, and both Reagan and Gorbachev had jointly concluded their 1985 Geneva summit with a pledge that “nuclear war cannot be won and must never be fought.” The brink-of-war idea is hype, out of character for Shultz. Nor was Gorbachev going to start a war. Months before, he had just been through the shattering and sobering experience of the Chernobyl nuclear disaster.

The summit ended without agreement on nuclear weapons. To those who witnessed the event, Reagan looked dour as he climbed into his limo. Failure was written on Shultz’s face as he addressed the world’s press, and U.S. negotiator Max Kampelman was near tears. In the movie, the ending is a happy handshake over Gorbachev’s agreement to allow the sister of cellist and conductor Mstislav Rostropovich to visit the United States. It was not that way. The Washington Post carried a two-line, front-page banner headline the next morning, proclaiming: “Reagan-Gorbachev Summit Talks Collapse as Deadlock on SDI Wipes Out Other Gains.”

Today, the nuclear arms control treaties that followed Reykjavik have expired or been abandoned. The world is on the cusp of a new arms race, far more complex and just as threatening as the last. We should learn a lesson anew from this film, that the weapons will not go away on their own. It takes people with vision and political willpower—courage and guts—like Reagan and Gorbachev.

September 2026
By Matthew Bunn and Jon Wolfsthal

Jack Mendelsohn, a far-seeing diplomat, family man, teacher, and friend who spent decades working to reduce nuclear dangers, died August 13, five days short of his 92nd birthday. The world is a safer place because of his tireless commitment to common sense and because of the countless people he helped train in national security, nuclear deterrence, and diplomacy who will carry on his legacy.

Jack served as a U.S. Foreign Service officer with the U.S. Department of State and the U.S. Arms Control and Disarmament Agency (ACDA). He was a member of the second Strategic Arms Limitation Talks (SALT II) and Strategic Arms Reduction Treaty (START) negotiating teams. He later held appointments as deputy director of the Arms Control Association and vice president of the Lawyers Alliance for World Security (LAWS), and taught at three universities.

Early in his Foreign Service career, Jack served in overseas posts ranging from Haiti to Poland. He then joined ACDA in 1972, as the SALT I negotiations concluded and the SALT II talks began. Jack soon rose to become the right-hand man to the SALT II delegation’s chief negotiator, U. Alexis Johnson, and proved indispensable, helping navigate a group with differing agency viewpoints, Washington officials unaware of on-scene dynamics, and the gulf between the U.S. and Soviet positions.

Later, Jack told historians that during the negotiations he had “an overriding sense” that continuing an “unfettered” nuclear competition was “costly” and “dangerous,” making negotiated arms control a vital tool for U.S. and world security.¹ This realization, an example of Jack’s innate common sense, led him and Johnson to consistently work to make negotiating progress, including the occasional use of UNODIR cables—an acronym for “‘unless otherwise directed,’ we intend to take this approach”—to hurry decisions along. Within the delegation, Jack was considered a straight shooter, and the Soviets appreciated his focused, nonpolemical approach.

After SALT II, Jack served at NATO headquarters in the late-1970s, supporting talks on conventional arms control in Europe and advising on how to respond to Soviet SS-20 missile deployments. He backed the initial U.S. view that no new nuclear forces were needed, given the thousands of nonstrategic nuclear weapons that the United States had in Europe, but that view shifted after he left, leading to deployment of the Pershing II ballistic missiles and ground-launched cruise missiles in Europe.

After a stint at the State Department focused on science cooperation, Jack returned to arms control as ACDA’s START representative in the early years of President Ronald Reagan’s tenure. Little progress was made in 1981-1983 because the Reagan administration was more focused on nuclear buildup and confrontation with the “evil empire,” while the Soviet delegation had little room to maneuver as an ailing Soviet leader Leonid Brezhnev gave way to short-lived successors until Mikhail Gorbachev assumed power in 1985.

The U.S. delegation to the START negotiations was led at the time by Ed Rowny, a hawkish retired U.S. Army general who had clashed with Jack on the SALT II delegation. Jack thought little of Rowny’s “absolutely non-negotiable” proposals and tensions ran high.²

Jack was planning to leave that assignment when Rowny sent a famous memo to Washington targeting many members of his delegation; he described Jack (and others) as favoring “progress at any cost.”³ Jack departed the assignment before the Soviet walkout in late 1983, well before arms control revived once Gorbachev came to power.

After START, Jack became dean of the Foreign Service Institute’s School of Language Studies, where one of his proudest accomplishments was converting many instructors from poorly paid adjuncts to full-time employees with benefits.⁴

On leaving government in 1985, Jack joined the Arms Control Association (ACA) as deputy director under its new president, Spurgeon Keeny. Over the next 13 years, Jack helped manage the organization’s work, wrote frequently, and appeared on television and radio. His diplomatic skills and close and warm personal relations with officials, reporters, academics, and experts all over Washington served him well in this challenging role. Together, Jack and Spurgeon created a formidable team with unmatched expertise on arms control topics. With Jack’s deft input, the association became one of the most influential and important national security organizations in the 1980s and 1990s.

For younger staffers like we were, Jack’s common sense, negotiating skill, and calm amid the constant controversies of those days were essential guideposts for our careers. He was always eager to take the time to hear the views of staff, holding court on a daily basis. Many of us considered the time at ACA as a type of (very) low-paid, never-ending graduate seminar on nuclear policy and Washington politics. Jack genuinely cared about mentoring the next generation of arms control professionals and invested in that effort again and again. Those who worked under him (and Keeny) have served as ambassadors; White House, State, Defense, and Energy department senior officials; Foreign Service and intelligence officers; and teachers.

Jack left the association in 1998 and spent a year as the John M. Olin distinguished professor of national security affairs at the U.S. Naval Academy, then served as vice president of LAWS, producing white papers on national missile defense (2000), the Comprehensive Nuclear Test Ban Treaty (2001), and a Chronology of Arms Control (2002). He also taught as an adjunct professor at George Washington University’s Elliott School of International Affairs, and later at American University. He was a dedicated teacher and mentor on arms control and broader issues of international security.

Broadly educated and ever curious, Jack would sometimes take a course on Shakespeare or philosophy, or spend an evening seeing a new play or hearing a science lecture. He was a devoted husband, father, and grandfather who at times lamented that arms control work sometimes kept him from his family. His daughter Kasia is now a senior official at the U.S. National Nuclear Security Administration.

Jack’s focused approach, instinct for finding compromises, and broad view of arms control as one tool of U.S. national security policy are qualities much in demand and need today. His humanity and warmth, sense of humor (with a seeming endless supply of comical nicknames and old jokes), and his ready smile and love will be deeply missed.

ENDNOTES

1. Jack Mendelsohn, oral history interview by Charles Stewart Kennedy, Association for Diplomatic Studies and Training, February 12, 1997.

2. Ibid.

3. After the memo was leaked, the Senate Foreign Relations Committee made it public (with the names redacted) in the course of the hearings on Kenneth Adelman’s confirmation as ACDA director. For one of many press accounts, see Michael Getler, “Target of Controversial Memo: Admiral on START Team Retiring,” Washington Post, April 22, 1983.

4. Mendelsohn interview.

September 2026

The Untold Story of China’s Nuclear Weapon Development and Testing
By Hui Zhang
MIT Press, 2025

In this new history of China’s nuclear weapons program through the 1996 testing moratorium, Hui Zhang draws on the publications of Chinese nuclear weapons scientists and engineers over the last three decades to revise and expand on standard accounts. Beginning in the 1990s, former employees of the Chinese nuclear program took to local print publishers and the internet to share personal narratives of their experiences in the development, production, and testing programs. Zhang’s volume incorporates these sources to revisit the early days of China’s nuclear program as well as the campaign, beginning in the late 1970s, to develop and produce a second generation of designs.

This second generation of weapons—prioritizing “miniaturization, mobility, penetrability, safety, and reliability,” according to the goals set by the Chinese government—was more successful than previously believed, Zhang argues. Connecting each nuclear test at the Lop Nur site to a specific purpose in the weapons program, the author finds that Chinese advances in warhead miniaturization had born fruit by 1996. By the time China ended testing at Lop Nur, it had warheads with yields and size efficiency roughly comparable to U.S. designs, he claims. Zhang concludes that modern Chinese missiles may be able to deliver at least twice the warheads typically assumed by open-source estimates. He also predicts that China has little left to gain from a resumption of nuclear testing—an assessment with renewed importance following U.S. allegations in February 2026 that China has conducted a secret, low-yield nuclear test explosion in June 2020.—XIAODON LIANG

The Most Awful Responsibility: Truman and the Secret Struggle for Control of the Atomic Age
By Alex Wellerstein
HarperCollins, 2025

Alex Wellerstein seeks to change the narrative around U.S. President Harry Truman’s decision to drop the atomic bomb on Hiroshima and Nagasaki in his book, The Most Awful Responsibility, by claiming that Truman was not fully aware of the consequences of his actions until after the bombs had been deployed in 1945.

Through a narrative-like analysis, the author uses historical sources to document that Truman actually did not have complete understanding of the Manhattan Project or the scope and scale of the atomic bomb during his presidency. Although Truman remained a defender of his use of the atomic bombs after World War II ended, Wellerstein states that “one gets the sense that his defense of the use of the bombs was less about trying to cleanse his [Truman’s] conscience than it was about cleansing the American conscience,” which Truman felt was his duty as president (emphasis as received).

Wellerstein argues that Truman was deeply opposed to nuclear weapons but was still willing to bear the burden of the decision to drop the first and only atomic bombs. The author emphasizes that after the bombing of Nagasaki, Truman did not move to halt all bombings on Japan but placed “the limitation … that there would be no further dropping of the atomic bombs.” Wellerstein also argues that this occurred when Truman’s work to centralize the responsibility for nuclear weapons in one person—the president—began. The author concludes that this change was not an effort to gain power but rather “to make sure [atomic bombs] were not used again.”—LIBBY FLATOFF