Reducing Nuclear Dangers Through Diplomacy
Jack Mendelsohn (1934-2026)
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.
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.
Matthew Bunn, is a professor of practice at the Harvard Kennedy School and faculty lead for the school’s “Managing the Atom” project. He was the editor of Arms Control Today in the early 1990s. Jon Wolfsthal, a U.S. nuclear policy fellow at Pax Sapiens and former senior director at the U.S. National Security Council, was the first senior research analyst for nonproliferation at the Arms Control Association from 1991 to 1995.
The Untold Story of China’s Nuclear Weapon Development and Testing
By Hui Zhang
The Most Awful Responsibility: Truman and the Secret Struggle for Control of the Atomic Age
By Alex Wellerstein
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
David Holloway’s book is a commanding update to the political history of nuclear weapons but exaggerates the ability of leaders of nuclear-armed states to control the prospect of nuclear war.
September 2026
By Douglas B. Shaw
A Towering Achievement of a Narrow Type
Nuclear Weapons: An International History
By David Holloway
Yale University Press, 2026
David Holloway’s Nuclear Weapons: An International History is a commanding, single-volume update to the political history of nuclear weapons. It brings novel international perspectives into a unified narrative. But the book’s focus on the perspectives of leaders of nuclear armed states comes at a cost: It pays less attention to the facts that those leaders often failed to grasp and exaggerates their already wild overestimation of their control over the prospect of nuclear war.
Holloway’s most important achievement is adding international dimension to the standard understanding of nuclear weapons history. He presents novel facts in rich context, beginning with the Soviet nuclear weapons program and building through later chapters that weave together narratives I had previously encountered only anecdotally by listening to people in India and China talk about their perspective on nuclear weapons. By Chapter 14, “Sino-Soviet Nuclear Relations, 1950-67,” and Chapter 15, “The Crisis of 1969,” I encountered astounding facts and perspectives that were entirely new to me.
From Billiard Ball to Breakable Egg
Holloway’s conclusion draws insightfully on Hedley Bull’s understanding that sovereignty is malleable, not fixed, and must change to accommodate weapons that deny “even the most powerful states” the ability to “guarantee their own survival without some form of cooperation or understanding.”1 The author understands nuclear weapons more deeply than most of the historical figures he describes: not merely as a tool of state power, but as a human invention that changed the Westphalian state’s viability as an instrument of human security.
Daniel Deudney’s work sharpens this vision. Deudney describes how nuclear weapons transformed states from materially robust “billiard balls” into existentially fragile “eggs” that must be protected by new types of institutions or shatter.2 Daniel Ellsberg brings the point into still clearer focus: Nuclear weapons form a single “doomsday machine,” to which multiple leaders hold triggers but which no one can independently render safe.3 Harry Truman put it starkly in his final State of the Union address: “War has changed its shape, and its dimension. It cannot now be a ‘stage’ in the development of anything save ruin for your regime and your homeland.”4
Rather than dwelling on failed proposals for world government or strict international control of nuclear weapons, Holloway traces the pressure the bomb exerted in shaping international politics. He notes that “the innate characteristics of the bomb made it an effective boundary marker,” suggesting that using nuclear weapons might take states beyond the map of international relations altogether into a future of uncertain governance.5 Holloway is rightly skeptical of brinkmanship and of the confidence some leaders placed in their own ability to know when to step back. He returns instead to the inescapable logic of Thomas Schelling’s “threat that leaves something to chance” under conditions of mutual vulnerability. As Holloway puts it, “the danger is not that the deterring power will decide on war, the danger is that war will occur independently of the wishes of either side.”6 Out of this, he traces the emergence of an internationally shared understanding of mutual vulnerability.
This keen insight into how nuclear weapons reshape sovereignty and the state never quite finds its footing within Holloway’s larger narrative, which centers on how world leaders sought influence and security by building and threatening to use nuclear weapons. Holloway identifies the immediate failures and persistent shortcomings of nuclear security, but he does not draw out their policy implications the way Alex Wellerstein does in Restricted Data: The History of Nuclear Secrecy in the United States. The gap between the assumption of state rationality that stable deterrence requires and the actual behavior of states shows up repeatedly in shibboleths that Holloway awkwardly seems to accept as settled wisdom: nuclear secrecy, brinkmanship, and strategic ambiguity.
Great Men, Miniscule Mafias
Holloway’s international history casts world leaders as main characters thwarted time and again by bureaucrats. He depicts these leaders as of two minds about the bomb: aware of the devastating implications of its use, yet unable to resist its presumed coercive power. British Prime Minister Winston Churchill characterized the hydrogen bomb as “a badge to the Royal Enclosure”; Mao Zedong put it more starkly: “In today’s world, if we don’t want to be bullied, we have to have this thing.”7
Holloway portrays history’s great men as gifted in judging how close they could bring a conflict to the brink of war without going further, yet routinely undone by their own governments’ quiet noncompliance with clear directions on managing nuclear weapons. Holloway introduced former British Defense Minister Denis Healey’s phrase “miniscule mafia,” describing the cabal of “civil servants and staff officers, to whom governments abdicated their responsibility for NATO strategy … because politicians did not have the time or energy to master the issues.”8 The author returns to this pattern repeatedly: political leaders of great powers issuing clear direction on nuclear policy, only to have bureaucrats, unaccountable to public scrutiny and dismissive of fundamental truths about nuclear war, overturn it.
The most common form of miniscule mafia behavior is an insistence on elaborate preparations for nuclear war-fighting across varied, improbable, nearly hopeless scenarios, at the expense of restraint intended to lower the risk of nuclear war. Holloway observes that “the leaders of the nuclear powers had come to share the view that, in some ill-specified but profoundly important way, nuclear war was unacceptable.”9 Yet he repeatedly documents officials responsible for military preparations rejecting that view in favor of insisting that victory was possible because otherwise the specific tasks assigned to them could not be completed. Examples include:
Holloway makes little reference to the human and environmental costs of nuclear weapons. Questions such as how many lives are lost just building, maintaining, and managing nuclear arsenals globally, or how many people would perish in the most planned-for nuclear exchanges, remain frustratingly out of his scope.
A Narrow Focus
Holloway favors political leaders and bureaucrats to the exclusion of dreamers. His omission of Leo Szilard undermines a crucial perspective on how nuclear weapons and their role in human affairs were first imagined.
The lineage runs backward from Szilard. In 1913, physicist Frederick Soddy—building on his 1909 book The Interpretation of Radium, which explained the scale of energy released by radioactive decay—wrote in The New York Times that harnessing the energy of radioactive transmutation would “revolutionize all existence.” H.G. Wells drew on Soddy’s work for his 1914 novel The World Set Free, which coined the term “atomic bomb.” Szilard, in turn, credited Wells’s novel with shaping his own thinking. In 1933, crossing a London street, Szilard suddenly realized that a chain reaction—as imagined by Wells—was the key to building an atomic bomb. That insight led him, in 1939, to draft the letter that Albert Einstein sent to U.S. President Franklin Roosevelt warning that a bomb of unprecedented power could be built.
This omission is striking. Without these facts, the reader gets no sense of how nuclear weapons and their social implications were imagined before they were pursued, and may struggle to see how any of it could have turned out differently.
Holloway’s history ends in December 1988, with Gorbachev’s address to the United Nations—just short of the Soviet collapse that followed, and disappointingly short of how interesting the story of nuclear weapons becomes immediately thereafter. Scholarly work by John Steinbruner, Ashton Carter, Steven E. Miller, and others on managing nuclear escalation gave U.S. Senators Sam Nunn and Richard Lugar the conceptual basis for a transformational vision: reversing the Cold War nuclear arms race through Cooperative Threat Reduction. That program went on to deactivate more than 7,600 strategic nuclear warheads and destroy hundreds of ICBMs and submarine-launched ballistic missiles, along with dozens of ballistic missile submarines.13
Omission of this period is frustrating for two reasons: It eclipses the essential question of what happens to nuclear weapons that are never used, and it feeds a common habit in nuclear policy discourse of dismissing the Cooperative Threat Reduction program’s extraordinary success as irrelevant to humanity’s nuclear future. As a new nuclear arms race accelerates, it is worth remembering that eventually every nuclear weapon produced will either be used in anger; abandoned as the authority responsible for it grows less capable, creating intolerable uncertainty; or verifiably eliminated. The international “miniscule mafia” would prefer to treat cooperative threat reduction as an irrelevant anachronism, rather than as a first, encouraging proof that avoiding nuclear war is technically possible.
The omission of the post-Cold War experience is also disappointing from a scholarly perspective because it fails to recognize important nuclear histories of states without nuclear weapons. Togzhan Kassenova’s 2022 book, Atomic Steppe: How Kazakhstan Gave Up the Bomb, describes in painful detail the human costs of nuclear weapons programs largely absent from Holloway’s account. Mariana Budjeryn’s 2022 book, Inheriting the Bomb: The Collapse of the USSR and the Nuclear Disarmament of Ukraine, sheds astonishing light on how nuclear weapons foster imperial control and undermine the emergence of civic identity. Malfrid Braut-Hegghammer’s 2016 book, Unclear Physics: Why Iraq and Libya Failed to Build Nuclear Weapons, unpacks confounding complexity about what makes nuclear weapons programs more or less successful.
A further missing chapter in the international history of nuclear weapons is the resurgence, and later collapse, of serious political efforts in the last generation to seek the peace and security of a world without these weapons. A series of Wall Street Journal op-eds by U.S. Cold War veterans—secretaries of state George Shultz and Henry Kissinger, Defense Secretary William Perry, and Senator Sam Nunn—broadened the political salience of nuclear danger, beginning with their January 2007 call, “A World Without Nuclear Weapons.”14 That public call to action was matched by careful technical work on how to achieve it—for example, the Hoover Institution’s Reykjavik Revisited conference, also convened in 2007, in which Holloway himself participated, and later the International Partnership for Nuclear Disarmament Verification.
In December 2008, building on decades of work highlighting the danger of accidental nuclear war, nuclear expert Bruce Blair partnered with more than 100 international political, civic, and military leaders to found Global Zero, dedicated to the elimination of nuclear weapons. In April 2009, President Barack Obama gave a landmark speech in Prague recommitting the United States to “seek the peace and security of a world without nuclear weapons.”15 The following year, Obama built on this “Prague Agenda” by convening the largest gathering of heads of state since the signing of the UN Charter: a nuclear security summit in Washington that turned global political attention into tangible commitments from dozens of governments to reduce nuclear risks. The summit reconvened in Seoul in 2012, The Hague in 2014, and Washington again in 2016. Unlike the first efforts immediately following World War II, these efforts cannot reasonably be mistaken for a world government, but are instead just the sort of “egg cartons” Deudney imagines to protect states against their new form of nuclear fragility.
In sum, Holloway’s book is a towering achievement of a narrow type.
ENDNOTES
1. David Holloway, Nuclear Weapons: An International History (Yale University Press, 2026), p. 575.
2. Daniel Deudney, “Nuclear Weapons and the Waning of the Real-State,” Daedalus, Vol. 124, No. 2 (Spring 1995), pp. 209-231.
3. Daniel Ellsberg, The Doomsday Machine: Confessions of a Nuclear War Planner (New York: Bloomsbury, 2017).
13. Cooperative Threat Reduction Program figures per the Defense Threat Reduction Agency’s official program history and Nunn-Lugar 20th-anniversary reporting.
14. George P. Shultz, William J. Perry, Henry A. Kissinger, and Sam Nunn, “A World Without Nuclear Weapons,” The Wall Street Journal, January 4, 2007.
15. “Remarks by President Barack Obama In Prague as Delivered,” U.S. National Archives, April 5, 2009.
The U.S. president acted once the 60-day negotiating window that the United States and Iran set for reaching a nuclear deal ended in August.
September 2026
By Kelsey Davenport
The 60-day negotiating window that the United States and Iran set for reaching a nuclear deal ended in August without an agreement, prompting U.S. President Donald Trump to announce additional economic pressure on Iran.
The two states reached a memorandum of understanding in June that was intended to end the conflict that began Feb. 28 with illegal U.S. and Israeli strikes. The memorandum also reopened the Strait of Hormuz to maritime traffic and set a 60-day window for concluding a final deal, including on Iran’s nuclear program. (See ACT, July/August 2026.)
Both the United States and Iran violated the ceasefire commitment over the 60-day window and failed to sustain a negotiating process. Although they did engage through mediators Pakistan and Qatar during that period, there was little focus on nuclear issues, and the two sides did not agree to extend the 60-day negotiating period. As the deadline approached, both sides made military threats but neither side appears poised to return to war.
Before the Aug. 17 expiration, Iranian Foreign Minister Abbas Araghchi told the Iranian Students News Agency Aug. 14 that the June memorandum of understanding marked “the end of the war, not a ceasefire.” The same day, Araghchi said in a post on Telegram that Iran has “not yet made a decision to restart negotiations with the United States.”
After previously claiming in early August that Iran and the United States were talking and that a deal on the Strait of Hormuz was close, Trump said in an Aug. 18 post on Truth Social that there “are no talks or conversations going, or scheduled with” Iran. He said the U.S. naval blockade on Iran “remains in full force and effect” but that the Strait of Hormuz is “open and operating.”
Maritime traffic through the Strait, however, remains well below prewar levels and Iran has targeted ships that do not coordinate passage with Tehran. After closing the waterway during the war, Iran is now seeking to charge ships for services through the Strait and is working with Oman, which also borders the waterway, on a deal that includes new shipping routes. Araghchi said in the Aug. 16 Telegram post that the “routes that previously existed are no longer functional, and a new route must be defined.” He said the resumption of shipping “depends on the fulfilment of other conditions that the United States must adhere to.”
Trump, however, has suggested that the United States should administer the Strait of Hormuz and charge a toll for transiting ships, which would be illegal under international law. He said Aug. 14 on Truth Social that after “we finish defeating Iran” he will be “declaring the Hormuz Strait a territory of the United States” and posted a map labeling the area a U.S. territory.
In response, Iranian Deputy Foreign Minister Kazem Gharibabadi said in an Aug. 14 post on the social media site X that the “Strait of Hormuz cannot be seized by a tweet, nor by aircraft carrier.” He said that the “Strait of Hormuz has been Iranian, is Iranian, and will remain Iranian.”
Despite continued threats to attack Iran, Trump appears to have shifted U.S. strategy and announced that Washington will be ratcheting up economic pressure on the country, presumably to push Tehran to negotiate. In an Aug. 19 post on Truth Social, Trump said he offered Iran an opportunity to make a deal, but Tehran “failed to take it.” He announced that the United States would now pursue “Economic Warfare” and put in place “the MOST CRUSHING ECONOMIC OPERATION EVER TAKEN AGAINST ANY COUNTRY.” He also said any country doing business with Iran will face economic consequences.
It is unclear exactly what measures Trump is considering to increase pressure. U.S. Treasury Secretary Scott Bessett told Newsmax Aug. 13 that the United States is already taking steps to dismantle Iran’s shadow banking system, which Tehran relied upon to move money.
Araghchi responded to the announcement by saying in an Aug. 19 post on X that “doubling down on failed policies will only bring further defeat—and enmity of Iranians.”
Although Tehran is moving to solidify control over the Strait of Hormuz, it does not appear to be taking any concerted steps to rebuild its nuclear program or increase its nuclear leverage.
Trump threatened to attack a site under construction near Natanz tied to Iran’s nuclear program known as Pickaxe Mountain, telling reporters July 21 that the United States “would be hitting that area very soon.” The threat, however, appeared motivated by actions Iran took before the Feb. 28 war, not recent activity.
The United States would likely need to use the Massive Ordnance Penetrator, the largest conventional weapon in the U.S. arsenal, to damage the facility, given how deeply buried it is. The United States also could try to target the tunnel entrances into Pickaxe Mountain using smaller conventional weapons.
Iran declared the site to the International Atomic Energy Agency (IAEA) as a centrifuge assembly facility, but the IAEA has never inspected the site. Foreign ministry spokesman Esmail Baghaei said in a July 22 briefing that there is no nuclear activity taking place at Pickaxe.
Baghaei’s comments came after The Wall Street Journal reported July 21 that Iran may have moved thousands of centrifuges, the machines used to enrich uranium, into the site after the 12-day war in June 2025. Israel shared that intelligence with the United States, according to officials quoted by the newspaper.
It is unclear if the centrifuge machines came from one of Iran’s known enrichment facilities or if they are machines that were produced but never installed or operated. The IAEA has warned for years that it cannot account for all of Iran’s centrifuges.
Trump suggested July 21, however, that Iran did not move any nuclear materials to Pickaxe Mountain, which would be necessary if Iran intended to enrich uranium at the location.
The U.S. president offered conflicting messages for his decision but he may have been trying to signal interest in renewed diplomacy with North Korea.
September 2026
By Kelsey Davenport
President Donald Trump announced that the United States would scale back a joint military exercise with ally South Korea because of the message it sends to North Korea.
Trump has offered conflicting rationales about why he ordered a shortening of the annual drill, but it appears that he is trying to signal interest in diplomacy with North Korea. He told reporters Aug. 19 that he expects to meet with North Korean leader Kim Jong Un by the end of the year.
In an Aug. 16 post on Truth Social announcing the decision, Trump wrote that he was “not happy” with U.S. participation in the joint military exercises because of his “very good relationship with Kim Jong Un.”
The drills “send a signal that is totally inappropriate and hostile” to North Korea, which has been “unthreatening and respectful” to the United States during his presidency, Trump said. But he also criticized the drills as expensive, saying most costs are “paid for by the United States of America (as usual!),” and complained that South Korea is not doing enough to support U.S. efforts against Iran. Trump implied he would have canceled the exercises outright, but it was “too late” to do so.
The drills, which began Aug. 17 and were set to run through Aug. 28, ended Aug. 21. The Defense Department said in an Aug. 18 statement that “there will be no degradation to U.S. training objectives” due to the shortened schedule.
South Korean President Lee Jae-Myung did not respond to Trump’s post directly, but he raised the issue during an Aug. 18 cabinet meeting. According to a report on the meeting issued by his office, “Lee emphasized that while creating peace without the need for conflict is of the utmost importance, preparation for the worst-case scenario is also necessary.” The readout stated that the August military exercises are defensive in nature and that South Korea has no intention of attacking North Korea or escalating tensions on the peninsula through it.
North Korea’s state-run Korean Central News Agency (KCNA) denounced the drill, despite the reduced duration and South Korea’s description of it as defensive. In an Aug. 19 commentary, KCNA accused the United States and South Korea of “hiding the aggressive and provocative nature of the largest-ever exercises.” The statement said the exercise “is pushing again the tensions on the Korean peninsula to the threshold of a war.”
The day after Trump announced a curtailment in the exercises, he told reporters that he has been in contact with Kim and that Kim responded to his request for a meeting.
Yet, Kim Yo Jong, the sister of North Korea’s leader, denied any contact with Trump. In an Aug. 19 statement on KCNA, she said the relationship between Trump and Kim “is still excellent,” but her brother is “not aware” of any communication. The “U.S. hostile policy toward [North Korea] has remained unchanged,” she said.
Kim Yo Jong also said the U.S. decision to shorten joint exercises with South Korea is “unworthy of comment” and suggested that the curtailment will not alter North Korea’s view of engagement with the United States. If the United States “calculates that it can propagate its recent measure as the one of so-called good faith, they will not get desired answer,” she said.
The last time the United States adjusted its military exercises with South Korea on short notice was in 2018, after Trump’s historic meeting with Kim in Singapore. (See ACT, July/August 2018.) During that meeting, Trump and Kim signed a declaration committing their two countries to denuclearization of the Korean peninsula. Trump and Kim met twice after that during the following year, but the negotiations achieved few tangible results before breaking down.
Since then, North Korea has taken steps to expand its nuclear weapons program, solidify the role nuclear weapons play in its defense, and strengthen its relationship with Russia. Pyongyang now says that North Korea will not negotiate with the United States unless Washington drops its demand for denuclearization.
When previously asked about Trump’s willingness to negotiate with Kim during his second term, the White House stated that dialogue should take place based on the Singapore summit declaration. It is unclear if Trump will move from that demand in order to meet with Kim.
The Lee administration has already deemphasized denuclearization. South Korea’s new strategy toward North Korea drops denuclearization as Seoul’s priority and emphasizes the need to pursue peaceful coexistence before the elimination of nuclear weapons, according to South Korean Unification Minister Chung Dong-young.
Chung outlined the new approach to negotiations with North Korea in a July 23 press briefing. He said that “the ultimate goal of denuclearization has not been abandoned, but denuclearization first has.” Chung said that the Lee administration’s decision to “reset the goals of its North Korea policy” to emphasize “peace first” is a more pragmatic approach that acknowledges the reality of the situation on the Korean peninsula.
He also said that if South Korea emphasizes denuclearization “at the entrance to dialogue, the reality is that dialogue cannot begin.” Instead of insisting on denuclearization early in the process, South Korea’s strategy will call for North Korea to halt nuclear weapons development and later roll it back.
North Korea’s state-run media did not respond directly to Chung’s remarks, but the Foreign Ministry said in a statement July 24 in KCNA that the United States, Japan, and South Korea cannot “bring up for discussion again the issue of ‘denuclearization,’ which was irreversibly and finally concluded.”
Lee’s willingness to deemphasize denuclearization, however, may make it easier for the Trump administration to move away from the Singapore declaration as a starting point for any new talks with North Korea.
Testifying to Congress, the officials said an ongoing review of U.S. nuclear forces will recommend additional limited options for nuclear warfighting below the strategic level.
September 2026
By Xiaodon Liang
An ongoing review of U.S. nuclear forces will recommend additional limited options for nuclear warfighting below the strategic level, according to senior Pentagon officials.
Undersecretary of Defense for Policy Elbridge Colby and the commander of Strategic Command, Adm. Richard Correll, previewed Aug. 5 the results of the review, first announced in March, to attendees of an annual conference hosted by Correll’s command near its Omaha headquarters. (See ACT, April 2026.)
The review will examine “rationally employable, limited options that advantage us and stand the chance of favorably managing escalation and not getting us into an inexorable spiral,” Colby said during a conference event.
The limited options referred to by the officials likely imply acquisition of more types of tactical nuclear weapons—weapons with a shorter range and smaller yield, and intended for tactical missions on the battlefield.
But neither official directly addressed whether the administration of President Donald Trump would increase the size of the deployed U.S. strategic nuclear force to match growth in the combined number of potential targets in Russia and China, a key policy decision deferred by the Biden administration. (See ACT, December 2024.)
Advocates for a strategic buildup argue that a larger U.S. force may be needed to deter Russia or China if the United States were to be involved in conflicts with both simultaneously or sequentially. Opponents argue it would trigger an acceleration of the arms race as Russia and China respond in kind.
An Aug. 5 story by NBC News reported that the review would de-emphasize strategic nuclear forces and traditional damage limitation requirements, which task U.S. troops with effectively preventing enemy nuclear forces from retaliating against a U.S. strategic first strike.
Colby spoke only obliquely regarding strategic forces and missions in Omaha. “We need to have a plausible plan that doesn’t [depend on] ‘Well, if we get to that point, we blow up the world,’ or … ‘We take them out, you know, problem solved,’” he said.
Although the United States has traditionally rejected Chinese requests to recognize mutual vulnerability between the two sides’ nuclear forces, Colby came close, noting that “We and China both have nuclear weapons, so nobody’s going to be in a position where they can absolutely dominate.”
He sought to contrast “credible,” “rational” tactical options that are currently lacking against strategic options that, if used, could “result in a catastrophe whose costs are way out of proportion to whatever we’re fighting about, or more plausibly cause the political leadership to say ‘No, I don’t want do that.’”
The move to downplay strategic superiority will meet skepticism in some corners of the Republican-controlled Congress. “It’s hard to imagine a study that is more out of line with President Trump’s stated position of making our nuclear deterrent great again,” an unidentified staffer told the authors of the NBC report.
Congress has already appropriated funding to open tubes on Ohio-class ballistic missile submarines and ordered the Pentagon to study and plan for uploading additional warheads to the Minuteman III intercontinental ballistic missile.
The legislature will likely greet the nuclear strategy review’s emphasis on tactical nuclear weapons with greater enthusiasm. The Senate Armed Services Committee’s draft of this year’s key policy bill recommends authorization of new air-launched and ground-launched tactical nuclear weapons. (See ACT, July/August 2026.)
These would supplement weapons already in the arsenal, such as the B61-12 gravity bomb and the W76-2 lower-yield warhead for the Trident II submarine-launched ballistic missile. The Navy is also planning to field a nuclear-capable sea-launched cruise missile by 2032, and the Air Force’s long-range standoff weapon—a new air-launched cruise missile presently entering full-scale production—and its selectable-yield warhead may also be relevant to tactical nuclear missions.
Colby and Correll confirmed that U.S. declaratory policy would remain unchanged, while providing little clue as to whether additional tactical nuclear weapons would be intended for initiating or responding to a nuclear conflict.
Both the 2018 and 2022 nuclear posture reviews declared that the United States might use nuclear weapons first in extreme circumstances in response to non-nuclear strategic attacks against itself or allies and partners.
Some U.S. analysts have called for a more explicit focus on the tactical use of nuclear weapons to blunt a potential Chinese invasion of Taiwan.
A 2022 report by Colby and a co-author recommended planning to target not only People’s Liberation Army troops, but also China’s defense industrial base with limited use of nuclear weapons.
In contrast, Correll told reporters on an Aug. 5 media call that the review contemplates “deterrence, first and foremost.”
A larger number of tactical launchers and platforms would “raise the threshold for consideration of theater nuclear employment by any potential adversary,” Correll said.
The strategy review will inform an update to the president’s nuclear weapons employment guidance. By law, the executive branch is required to provide a summary of the changes to Congress 60 days before they are implemented.
Observable changes “do not call into question present weapons performance,” the JASON group of scientists reported.
September 2026
By Xiaodon Liang
The plutonium pits at the core of U.S. nuclear weapons are “aging slowly” and observable changes “do not call into question present weapons performance,” a panel of independent technical experts concluded.
The JASON group of scientists, which has long served as independent advisers to the U.S. government, encourages the National Nuclear Security Administration (NNSA), however, to continue “establishing pit production capabilities that may be needed to provide options to mitigate any future aging-related issues.”
That recommendation was one of several in the executive summary of a JASON study completed in March. The group also called on NNSA to accelerate construction of the Scorpius machine, a linear accelerator that will create radiographic images of subcritical plutonium experiments.
By fiscal year 2030, the NNSA will be on track to better understand plutonium pit performance degradation as it continues executing a decade-long research plan into pit aging begun in 2021, the study predicted.
The NNSA released the unclassified executive summary Aug. 7 but has withheld the full report, which Congress commissioned in the fiscal year 2024 energy and water appropriations act.
The conclusions of the new JASON report may complicate the NNSA’s rationale for prioritizing resumption of large-scale plutonium pit production.
During the Cold War, the United States produced plutonium pits at scale at the Rocky Flats Plant in Colorado. After Rocky Flats closed in 1989, Los Alamos National Laboratories produced 31 pits for the W88 warhead program between 2007 and 2011.
The agency is currently executing a plan adopted in 2018 to produce 30 pits per year at Los Alamos and 50 per year at the future Savannah River Plutonium Processing Facility. Congress mandated in 2019 that the NNSA be able to produce 80 pits annually.
The JASON group last conducted a full study of plutonium aging in 2006, at which point it concluded that “most primary types have credible minimum lifetimes in excess of 100 years,” referring to the first stage of a nuclear weapon within which pits are a key component.
The executive summary to the new study notes that NNSA began observing “some aging effects” in 2010. The NNSA’s current plans for pit production were in part justified by a 2019 two-page abbreviated assessment by the JASON group of the state of research into plutonium aging, which called for pit production to be re-established “expeditiously.”
Although Trump administration officials expressed confidence earlier this year that plutonium pit production at Los Alamos could be accelerated to produce 100 pits by 2028, construction at Savannah River remains at an early stage. (See ACT, April 2026.)
In its fiscal 2027 budget request, the NNSA described a $25 billion working cost estimate for the Savannah River facility as a “budgetary placeholder.” (See ACT, June 2026).
The agency anticipates completion of the facility by between late 2031 and mid-2035. In February, the Government Accountability Office (GAO) reported that NNSA employees were skeptical of the timeline.
The GAO also said that contractor performance at Savannah River has been unsatisfactory, with delays and inadequacies in the delivery of designs. In February, NNSA decided to open for tender the next management and operating contract for the Savannah River Site, in a sign of frustration with the current consortium led by Fluor Corp. (See ACT, June 2026.)
The agency nonetheless exercised
an option Aug. 10 to extend the current contract for one year, through September 2027.
The NNSA said the move would “ensure continuity and stability of the contractor workforce” as it assesses bids.
U.S. Deputy Secretary of Energy James Danly also raised questions about the NNSA’s plutonium pit production plans in August 2025, tasking the Energy Department’s Office of Enterprise Assessments to conduct an internal review.
Danly set a Dec. 9 deadline for the process and Congress later instructed the NNSA in its fiscal 2026 energy and water appropriations act to provide a copy of the review report.
In July, the nonprofit organization Nukewatch New Mexico filed a Freedom of Information Act lawsuit in a bid to obtain the internal report.
His announcement that the agreement is contingent upon the kingdom’s recognition of Israel throws the deal’s future into doubt.
September 2026
By Kelsey Davenport
The United States signed a nuclear cooperation agreement with Saudi Arabia, but President Donald Trump’s announcement that the deal is contingent upon the kingdom’s recognition of Israel throws the deal’s future into doubt.
U.S. Energy Secretary Chris Wright and Saudi Energy Minister Prince Abdulaziz bin Salman signed the nuclear cooperation agreement, commonly known as a “123 agreement,” July 20 and July 22, respectively.
The agreement, which is necessary before U.S. companies can sell certain nuclear materials and related technologies, was expected after the White House announced a framework for nuclear cooperation with Saudi Arabia in November 2025. (See ACT, December 2025.)
In a statement issued after the signing, Wright said that the agreement upholds “the highest standards of nuclear safety and nonproliferation.” The deal, however, supports Saudi Arabia’s plan to acquire uranium enrichment technologies necessary to produce nuclear fuel, without insisting on more intrusive International Atomic Energy Agency (IAEA) monitoring. That same technology can be used to produce fissile material for nuclear weapons.
Saudi Arabia does not have a nuclear weapons program and pledged as a member of the nuclear Nonproliferation Treaty (NPT) not to acquire such weapons, but officials, including Crown Prince Mohammed bin Salman, have threatened to build nuclear weapons if Iran does. (See ACT, June 2018.) According to documents obtained by Arms Control Today, Trump formally signed the required presidential determination that the agreement does not “constitute an unreasonable risk to common defense and security” July 16, despite those threats.
The day after Wright signed the deal, Trump posted on Truth Social that the nuclear cooperation agreement “will be approved, but is totally subject to Saudi Arabia joining the very respected and successful Abraham Accords.”
Saudi Arabia has not responded to Trump’s demand regarding the Abraham Accords, a diplomatic framework that led several countries, including the United Arab Emirates and Bahrain, to recognize Israel, but Israeli Prime Minister Benjamin Netanyahu praised the decision. In a July 23 statement, Netanyahu said that Saudi Arabia joining the accords would be a “historic leap forward for peace in the Middle East.”
The Trump administration submitted the nuclear cooperation agreement and the required nonproliferation assessment to Congress for a 90-day review, as required by the Atomic Energy Act on Aug. 24.
The deal is expected to receive pushback from Republican and Democratic legislators, but it is unclear if there will be enough opposition to pass a joint resolution of disapproval, which would block the deal from going forward.
Several members of Congress have already expressed concerns about the agreement because it abandons longstanding conditions for U.S. nuclear cooperation that have bipartisan support. Sen. John Kennedy (R-La.) told the CBS show, “Face the Nation,” July 26 that he was not comfortable with the nuclear cooperation agreement as presented but said, “I don’t think it’s going to happen, anyway.”
All U.S. nuclear cooperation agreements must meet certain nonproliferation criteria enumerated in Section 123 of the Atomic Energy Act, such as the requirement that all nuclear material transferred under an agreement be under IAEA safeguards. Congress, however, has generally supported requiring states to adhere to even more intrusive IAEA monitoring and pushed them to forgo the option to enrich uranium and reprocess plutonium, an approach to nuclear cooperation agreements known as the “gold standard.”
The Trump administration already acknowledged in a November 2025 report to Congress that the nuclear cooperation agreement with Saudi Arabia will not meet the gold standard. The text of the deal confirms that the United States will support Saudi Arabia’s decision to develop uranium enrichment and will not require it to negotiate a more intrusive IAEA safeguards agreement, known as the additional protocol. (See ACT, April 2026.)
The additional protocol, which was finalized in 1997 after illicit nuclear programs in Iraq and North Korea exposed gaps in the NPT-required safeguards, gives the IAEA expanded access to a country’s nuclear sites and additional information about the program. The United States has long supported the universalization of the additional protocol and pushed for its inclusion in nuclear cooperation agreements.
In the November 2025 report to Congress, the Trump administration said that the United States would implement a bilateral safeguards agreement with Saudi Arabia in lieu of the additional protocol. A document outlining the safeguards arrangements submitted to Congress Aug. 24 includes additional details on the information and access that Saudi Arabia will provide the IAEA.
The documents confirm that cooperative U.S.-Saudi nuclear activities could include uranium enrichment, a capability that Riyadh says it wants to develop in order to produce nuclear reactor fuel. (See ACT, March 2023.)
The nuclear cooperation agreement requires a two-year feasibility study that examines the commercial viability of uranium enrichment in Saudi Arabia. If the study supports enrichment, one option could be for the United States to build and operate an enrichment facility in Saudi Arabia to prevent Riyadh from having direct access to U.S. enrichment technology—but it is unclear how Washington would prevent information about enrichment from leaking to Saudi officials or secure the facility in the event of conflict. The United States has never supplied enrichment technology as part of a nuclear cooperation agreement.
According to The Wall Street Journal, if the study does not support enrichment, Saudi Arabia will be free to pursue uranium enrichment domestically or with another foreign partner after 10 years.
Members of Congress have also raised concerns about the implications of the Saudi nuclear agreement on proliferation risks in the Middle East. Sen. John Barrasso (R-Wyo.) warned that the deal could increase proliferation risks in the region and make it more challenging to get Iran to give up uranium enrichment. Sen. Chris Murphy (D-Conn.) said it could “end up pushing Iran closer to a nuclear weapon.”
As executive director for the past quarter-century, Daryl G. Kimball has led the Arms Control Association through setbacks and breakthroughs, gloom and hope in the arms control field.
September 2026
By Thomas Countryman
A couple of years ago, the Arms Control Association celebrated its 50th anniversary as one of the leading nongovernmental organizations dedicated to confronting the risk of planetary suicide by nuclear weapons. We marked last month with an equally significant milestone: Daryl G. Kimball has now led our association as executive director through 25 years of setbacks and breakthroughs, gloom and hope in the arms control field.
Daryl came to this work inspired partly by his family. His mother organized and campaigned tirelessly to demand a cleanup of the consequences of the government’s uranium enrichment program near their home in Ohio. His father was a noted scholar of U.S. nuclear policy.
Daryl first came to Washington in the Scoville Fellowship, the innovative program that—to this day—gives so many scholars and activists their first experience with arms control and nonproliferation issues, and from which the ACA team has drawn several of its top experts.
Daryl started not just in research, but in media and public education efforts that still inspire the association’s efforts to be not just a think tank, but a “think and do” tank. At Physicians for Social Responsibility, his leadership and partnership helped achieve a U.S. Congress resolution endorsing a nuclear testing moratorium in 1992 and engendered administration and congressional support for negotiation of the Comprehensive Test Ban Treaty (CTBT).
Following the dissolution of the Soviet Union, the 1990s were a time when many of us believed that still more significant progress could be made toward a world free of nuclear weapons. In 1997, Daryl became the executive director of the Coalition to Reduce Nuclear Dangers, which brought together 17 of the largest nongovernmental organizations to push for ratification of the CTBT and demand additional reductions in the world’s nuclear arsenals.
Asked by the ACA Board of Directors to become the association’s executive director in 2001, Daryl brought the same focus and drive to an organization already prominent not just for its longevity, but for its credibility and objectivity in analyzing the national security choices facing the United States and the world. The ACA has become a prime forum for senior officials in successive U.S. administrations, and even future presidents, to outline their vision of managing nuclear risk. When we had administrations whose officials were open to dialogue, ACA’s voice was not just heard, but respected, and—yes—influential. In 2011, the association received the MacArthur Award for Creative & Effective Institutions for its ability to address “pressing national and international security challenges with an impact that is disproportionate to its small size.”
All of us who have worked with or for Daryl—and the list of senior officials and creative thinkers who began their careers at ACA is long and impressive—appreciate the asset that best marks a successful leader: genuine appreciation for his coworkers and an active concern for their professional advancement. It matters no less in a small organization than in a lumbering bureaucracy, and it shines through in Daryl’s daily work.
Our challenges today are aggravating: an economic environment that puts the financial squeeze on nongovernmental organizations in national security and other spaces; an ever more crowded public marketplace of ideas, where an even-tempered voice strains to be heard; an erosion of the arms control agreements that have provided a small measure of peaceful breathing to the world; a government disinclined either to listen, or to explain, to the experts whose experience has contributed so much to decades of complex national security issues.
But we do not have the luxury of being discouraged, the time to indulge despair, nor the option to admit defeat. For a quarter-century, we have relied on Daryl Kimball’s judgment, focus, and energy to confront challenges great and small. This would be a good moment for all of our readers to express our thanks to him and honor his significant contributions.
Thomas Countryman, chairman of the board of the Arms Control Association, is a retired U.S. foreign service officer who served as acting undersecretary of state for arms control and international security, among other senior positions.
This analysis was updated on September 1, 2026, to take into account details of the text of the agreement and associated documents after they had been transmitted to Congress.
