On April 15, 2026, Harvard Kennedy School’s Belfer Center for Science and International Affairs launched its new Carnesale Convenings series¹ with a question central to American national security: can a “frayed” nuclear nonproliferation regime survive rising geopolitical tensions and new proliferation pressures? Belfer Center Director Meghan O’Sullivan moderated a wide-ranging discussion to answer that essential question with speakers including Graham Allison (Douglas Dillon Professor of Government at Harvard University), Rose Gottemoeller (William J. Perry Lecturer, Freeman Spogli Institute for International Studies and Research at Stanford University), Laura Holgate (Former Ambassador to the IAEA and Belfer Center Senior Fellow), and Matthew Bunn (James R. Schlesinger Professor of the Practice of Energy, National Security, and Foreign Policy at Harvard Kennedy School). Moving between moments of optimism and unease, the panel grappled with the prospects of new nuclear-armed states, the erosion of traditional arms control, the growing imprint of great power politics on the IAEA, and NATO’s efforts to send a clear deterrence message to Moscow.

Iran and Nuclear Proliferation²

Graham Allison’s early remarks meditated on President John F. Kennedy’s March 1963 concern that the United States could face “a world in which 15 or 20 or 25 nations” possessed nuclear weapons by the 1970s. Noting the steep trend line in nuclear proliferation prior to Kennedy’s 1963 warning, Allison iterated the remarkable fact that only nine states currently possess nuclear weapons and emphasized the quiet success of the nuclear nonproliferation regime. 

Yet Allison bets “Nine will not be the number [of nuclear-armed states] at the end of the next decade.” While “sad to say,” he believes it is only rational for more states to reconsider developing an independent nuclear deterrent considering doubts about the U.S.’s extended deterrent and the U.S.-Israeli campaign against Iran. He believes the United States would not have attacked Iran had Iran been “North Korea”—i.e., nuclear-armed. 

While Allison views proliferation as more likely than not, he also envisioned a potential future in which the United States, China, and “maybe Russia” could agree to work jointly to limit any future proliferation and find a common interest in preventing proliferation in East Asia, a region Allison views as increasingly susceptible to proliferation pressures. 

Matthew Bunn similarly fears that the current war with Iran “has greatly increased” Iran’s incentives to build a nuclear weapon, and he considers the U.S. use of force for nonproliferation purposes both “illegal and ineffective.” In his assessment, the odds of Iran developing a nuclear weapon within a decade are “bigger, rather than smaller” than they were a year ago.

However, Bunn noted significant “costs, risks, and dilemmas” along the path to a secure nuclear deterrent, which ultimately make him “one of the last standing optimists” willing to wager that only nine states will possess nuclear weapons in the next decade. Bunn explained how violations of the Nuclear Non-Proliferation Treaty (NPT) trigger cutoffs in nuclear-materials deliveries and U.S. sanctions. As the current war with Iran shows, enrichment runs the risk of preventative strikes and developing a credible deterrent requires more than the ability to produce a warhead. “Even once you have nuclear weapons, it’s not much of a deterrent until you have a survivable nuclear force that is deliverable,” Bunn commented. In short Bunn argues that while the war has increased Iran’s desire to pursue a nuclear weapon, its nuclear program has been set back and the costs to obtain a secure nuclear deterrent, for any state, remain steep.  

The Future of Arms Control & The Three-Peer Problem

Stanford University’s Rose Gottemoeller highlighted that emerging technologies must be considered when evaluating the possibility of arms control, including space agreements. Bunn and Allison likewise noted space, counterspace, AI, cyber, and advanced conventional strike capabilities make contemporary strategic issues far more complex. 

Regarding space-based systems, Gottemoeller sees “fantastic monitoring opportunities” available to the United States, Russia and other countries, and value in reevaluating DoD’s previous hesitancy to “go down the verification route” on the Outer Space Treaty due to advances in verification capabilities. Gottemoeller believes the United States can continue to approach arms control agreements with the Russians and Chinese “in the pedigree of SALT,” and perhaps even leverage U.S. and Chinese leadership in AI to set “guardrails” on emerging technologies. 

Allison sounded a skeptical tone, expressing concern that we will come to see SALT, START, and New START as “relics of the past.” He assesses the current moment bears resemblance to the early days of arms control negotiations in which experts debated and iterated proper accounting rules and verification mechanisms. 

Beyond 21^st century technical challenges, O’Sullivan noted that China’s nuclear build up has introduced a “three-peer problem” into the arms control equation. Bunn added, “You could have a bilateral deal with Russia, if you knew where China was going,” but “if there’s no predictability, no restraint, it makes it difficult.” Allison views China’s nuclear build up as rational and potentially overdue but acknowledges it will “absolutely have a major impact” on how the U.S. assesses its own requirements. 

Bunn thinks there is a “very serious danger” that The United States, Russia, and China may engage in a new, “probably more slow-moving” nuclear arms race. The “vertical trajectory” of China’s nuclear build up, uncertainty regarding its intended ceiling, and the long-standing U.S. policy preference to “target all of the nuclear forces of its adversaries,” have pushed nuclear policy discussions from questions regarding the “next round of reductions” to evaluating whether to “leave the New START limits behind.” Ultimately, Bunn believes a future arms control regime will not consist of “200-page treaties,” but might be pulled together through political commitments, executive agreements, and other protocols.

Extended Deterrence & Collective Security 

Gottemoeller argued that NATO still possesses a credible deterrent despite rifts in the transatlantic alliance. While “there is no question [that] Donald Trump has shaken the faith of our allies,” she stated, allies cannot “be absolutely sure” that Trump would not respond to a nuclear strike on a NATO member in-kind. Allison and Gottemoeller suggested the current ambiguity may be sufficient to give Vladimir Putin pause, given the immense consequences of miscalculating NATO’s resolve to use nuclear weapons in defense of an alliance member. Bunn added, “to deter an adversary you only need 5% credibility, but to assure an ally you need 95%.”

Gottemoeller argued that NATO members should show that the “extended nuclear deterrent is fit for purpose” and signal their readiness “to participate in the extended nuclear deterrent mission if necessary.” Along these lines, she noted how NATO uncharacteristically advertised their latest Steadfast Noon training exercises in October 2025, “sending a deterrence message to Moscow.” 

Ultimately, she assesses, “the NATO capability has never been better,” noting the completed deployment of the B61-12—NATO’s ”most advanced warhead,” refurbished nuclear basing and handling facilities in Europe, and alliance member agreements to purchase and certify the F-35 for nuclear missions. Gottemoeller reiterated, the extended deterrent has “never been better fit for purpose with all the allies participating, not just the basing states.”

Geopolitics and the IAEA

O’Sullivan and Holgate reflected on how renewed great power competition has hindered the efficacy of international institutions. Holgate shared, “geopolitics have invaded what had been for so long considered a technical agency. “Russia, in Holgate’s view, works “actively to undermine” the IAEA’s independence and verification tools to protect “client states” such as Iran and Syria.

China, on the other hand is “flooding the zone with Chinese staffers,” coopting the language of sustainable development to present national projects like the Belt and Road Initiative as internationally condoned and uses its committee positions to present IAEA development funds as “a Chinese brand,” Holgate said.

China and Russia are not the only parties pursuing geopolitical goals at the IAEA. Holgate recalled the message she received from Washington following Russia’s invasion of Ukraine was: “ostracize Russia… We need to push back on them in every forum.” This, in Holgate’s assessment, “completely sucked diplomatic energy out of the room” and made it difficult to do “affirmative things.”

Conclusion

As Allison emphasized, “History… does have an arc, and trend lines frequently continue along the path that they run. JFK’s quote was a forecast of nuclear anarchy that would have been a word in which we would not have been able to live our lives… we should be thankful for the many, many people who have played a role in [the] successive chapters [of the nuclear nonproliferation regime].” Like Kennedy in 1963, the panelists hope to avoid a world in which the United States faces a multitude of nuclear-armed states and concluded the panel with suggested actions to mitigate proliferation dangers. Bunn believes that the United States behaving “as more-reliable partner for its allies” can make the nonproliferation regime more robust.  

Holgate argues for “bolstering” the IAEA’s budget and verification capabilities so it can provide  assurance to countries that their neighbors aren’t “building a bomb in the basement” while they develop civilian nuclear energy programs. She sees opportunities to create “safeguards-by-design” in new, fourth-generation nuclear reactors that reduce their usefulness to covert weapons programs. 

Gottemoeller thinks the U.S. and allies can change their approach to the NPT review cycle. Rather than “getting wrapped around the axle because we can’t get consensus on formal diplomatic documents,” she believes the U.S. and P5 partners can find ways to move the treaty forward and sustain cooperation in proliferation issues in the absence of a consensus document. 

While proliferation pressures may be making themselves felt, time will tell if Allison’s or Bunn’s proliferation wager is correct, and whether the international community will find common cause in support of the IAEA the NPT as advocated for by Holgate and Gottemoeller. 

Endnotes

1. The event inaugurated the Carnesale Convenings, a new Belfer Center series in honor of former Kennedy School Dean, Harvard Provost, and UCLA Chancellor Albert Carnesale, whose scholarship has made central contributions to nuclear policy and other fields.
2. In September 2025 the Belfer Center, Carnegie Endowment for International Peace, and Nuclear Threat Initiative published a report outlining how the U.S. should confront nuclear proliferation in the 21^st century to avoid Kennedy’s nightmare scenario. Read the report here.

Photo courtesy of Harvard Kennedy School's Belfer Center for Science and International Affairs.