Seeking Verifiable Destruction of Nuclear Warheads

A longstanding conundrum surrounding efforts to negotiate reductions in nuclear arsenals is how to verify the physical destruction of nuclear warheads to the satisfaction of an opposing party without disclosing classified weapons design information. Now some potential new solutions to this challenge are emerging.

Based on tests that were conducted by the Atomic Energy Commission in the 1960s in a program known as Cloudgap, U.S. officials determined at that time that secure and verifiable weapon dismantlement through visual inspection, radiation detection or material assay was a difficult and possibly insurmountable problem.

“If the United States were to demonstrate the destruction of nuclear weapons in existing AEC facilities following the concept which was tested, many items of classified weapon design information would be revealed even at the lowest level of intrusion,” according to a 1969 report on Demonstrated Destruction of Nuclear Weapons.

But in a newly published paper, researchers said they had devised a method that should, in principle, resolve the conundrum.

“We present a mechanism in the form of an interactive proof system that can validate the structure and composition of an object, such as a nuclear warhead, to arbitrary precision without revealing either its structure or composition. We introduce a tomographic method that simultaneously resolves both the geometric and isotopic makeup of an object. We also introduce a method of protecting information using a provably secure cryptographic hash that does not rely on electronics or software. These techniques, when combined with a suitable protocol, constitute an interactive proof system that could reject hoax items and clear authentic warheads with excellent sensitivity in reasonably short measurement times,” the authors wrote.

See Physical cryptographic verification of nuclear warheads by R. Scott Kemp, et al,Proceedings of the National Academy of Sciences, published online July 18.

More simply put, it’s “the first unspoofable warhead verification system for disarmament treaties — and it keeps weapon secrets too!” tweeted Kemp.

See also reporting in Science Magazine, New Scientist, and

In another recent attempt to address the same problem, “we show the viability of a fundamentally new approach to nuclear warhead verification that incorporates a zero-knowledge protocol, which is designed in such a way that sensitive information is never measured and so does not need to be hidden. We interrogate submitted items with energetic neutrons, making, in effect, differential measurements of both neutron transmission and emission. Calculations for scenarios in which material is diverted from a test object show that a high degree of discrimination can be achieved while revealing zero information.”

See A zero-knowledge protocol for nuclear warhead verification by Alexander Glaser, et al, Nature, 26 June 2014.

But the technology of nuclear disarmament and the politics of it are two different things.

For its part, the U.S. Department of Defense appears to see little prospect for significant negotiated nuclear reductions. In fact, at least for planning purposes, the Pentagon foresees an increasingly nuclear-armed world in decades to come.

A new DoD study of the Joint Operational Environment in the year 2035 avers that:

“The foundation for U.S. survival in a world of nuclear states is the credible capability to hold other nuclear great powers at risk, which will be complicated by the emergence of more capable, survivable, and numerous competitor nuclear forces. Therefore, the future Joint Force must be prepared to conduct National Strategic Deterrence. This includes leveraging layered missile defenses to complicate adversary nuclear planning; fielding U.S. nuclear forces capable of threatening the leadership, military forces, and industrial and economic assets of potential adversaries; and demonstrating the readiness of these forces through exercises and other flexible deterrent operations.”

See The Joint Operating Environment (JOE) 2035: The Joint Force in a Contested and Disordered World, Joint Chiefs of Staff, 14 July 2016.

New FAS Nuclear Notebook: Chinese Nuclear Forces, 2016

Click on image to download Notebook.

By Hans M. Kristensen and Robert S. Norris

China’s nuclear forces are limited compared with those of Russia and the United States. Nonetheless, its arsenal is slowly increasing both in numbers of warheads and delivery vehicles.

In our latest FAS Nuclear Notebook on Chinese nuclear forces published in the Bulletin of the Atomic Scientists, we estimate that China has a stockpile of about 260 nuclear warheads for delivery by a growing diversity of land- and sea-based ballistic missiles and bombers.

Changes over the past year include fielding of the new dual-capable DF-26 road-mobile intermediate-rage ballistic missile, the reported fielding of a new nuclear version (Mod 6) of the DF-21 road-mobile medium-range ballistic missile, more flight-tests of the long-rumored DF-41 road-mobile intercontinental ballistic missile, and the slow readying of the Jin-class (Type 094) nuclear-powered ballistic missile submarines.

China is also modernizing its aging fleet of H-6 bombers, some of which may have a secondary nuclear role.

Although China is still thought to be fielding more DF-31A launchers, the overall number of ICBM launchers has not increased since 2011 but remained at 50-75 launchers. The oldest of these, the liquid-fuel DF-4, apparently has an extra load of missiles but is thought to be close to retirement. None of the new ICBMs are thought to have reloads. Continue reading

President’s Message: What Will the Next President’s Nuclear Policies Be?

The presidential candidates’ debates will soon occur, and the voters must know where the candidates stand on protecting the United States against catastrophic nuclear attacks. While debating foreign policy and national security issues, the Democratic and Republican candidates could reach an apparent agreement about the greatest threat facing the United States, similar to what happened on September 30, 2004. During that first debate between then President George W. Bush and then Senator John Kerry (now Secretary of State), they appeared to agree when posed the question: ”What is the single most serious threat to the national security to the United States?” Kerry replied, “Nuclear proliferation. Nuclear proliferation.” He went on to critique what he perceived as the Bush administration’s slow rate of securing hundreds of tons of nuclear material in the former Soviet Union.

When Bush’s turn came, he said, “First of all, I agree with my opponent that the biggest threat facing this country is weapons of mass destruction in the hands of a terrorist network. And that’s why proliferation is one of the centerpieces of a multi-prong strategy to make the country safer.”[1] President Bush also mentioned that his administration had devoted considerable resources toward securing nuclear materials in the former Soviet Union and elsewhere.

Despite this stated agreement, the two candidates disagreed considerably on how to deal with nuclear threats. Today, the leading Democratic and Republican candidates appear to be in even further disagreement on this issue than Bush and Kerry, while nuclear dangers arguably look even more dangerous. I will not analyze each candidate’s views, especially because their views could change between the time of writing this president’s message in late June and the start of the debates in September. I think it is more useful here to outline several of the major themes on nuclear policy that should be addressed in the campaign and during the debates.

The most fundamental theme is: what is the role or roles of U.S. nuclear weapons? Deterrence is the easy answer, but against what or whom? That is, should nuclear weapons only be used when another nuclear-armed state uses them against the United States or U.S. allies or should the mission be expanded to include deterrence against massive biological attacks, for instance? Assuming the next president wants his policy team to elucidate that the sole purpose of nuclear weapons is solely for deterring others’ use of nuclear weapons, the next question is: should the United States have a no-first-use policy of not launching nuclear weapons before others launch nuclear weapons?

Such a policy would emphasize having nuclear weapons that would be secure against a nuclear attack that would come first from an enemy. For example, deployed submarines underneath the surface of the oceans would provide this type of secure force, whereas land-based nuclear-armed missiles and bombers could be more vulnerable to an incoming attack. Would the next president want to reduce the nuclear triad to a single leg of ballistic missile submarines? This decision would require considerable political courage and would have to withstand opposition from proponents who would want to keep the Air Force’s legs of the triad of intercontinental ballistic missiles and strategic bombers. However, the Air Force could transform its nuclear forces to have solely conventionally-armed missiles and bombers and in effect, it could have more militarily usable weapons that would not have to cross the high threshold of nuclear use.

Another argument for shifting to having just submarines deploy nuclear weapons is the cost savings from having to maintain nuclear arms for land-based missiles and bombers. This leads to the debate topic of whether the United States should spend up to $1 trillion in the coming decades on “modernizing” its nuclear forces. All three legs of the triad are showing their age. Each leg will require $100 billion or more to upgrade the launching platforms of missiles, bombers, and submarines, and in addition, there would be several $100 billion more in refurbishing and maintaining the half dozen types of nuclear warheads plus the related infrastructure costs. Would a presidential candidate seize the opportunity to save hundreds of billions of dollars by smartly downsizing U.S. nuclear forces?

The candidates would have to confront the promises made by the Obama administration to key Republican senators to “modernization” of the nuclear arsenal. This commitment was a crucial part of the bargain to convince enough Republican senators to vote in favor of the New START agreement with Russia in 2010. On June 17, 2016, Senator John McCain (R-Arizona) and Senator Bob Corker (R-Tennessee) sent a letter to President Obama to remind him of this commitment.[2] Senator Dianne Feinstein (D-CA) and former Under Secretary of State Ellen Tauscher have called for Congress not to fund the proposed nuclear-armed cruise missile, known as the Long Range Standoff Weapon (LRSO), because: there is no compelling military need; it could lower the threshold of nuclear use; and it is too costly at an estimate of up to $30 billion.[3]

New START was a relatively modest reduction in strategic nuclear forces. The tough challenge for the next president is whether further reductions with Russia are even possible given the heightened tensions over Ukraine and other sticking points between Russia and NATO, as well as between Russia and the United States. Going much lower in numbers of strategic nuclear arms might require a rethinking of the nuclear weapons configurations in both nuclear superpowers. Thus, the next president will need a highly capable team who will understand U.S.-Russia relations, the concerns of certain NATO allies, the concerns of East Asian allies, namely Japan and South Korea, as well as the effect on China.

China has remained apart from nuclear arms reductions, although Chinese leaders have made their views clear that they want to ensure that China has a secure nuclear deterrent. While China has for decades been content to have a relatively small nuclear force, there have been signs in recent years of a buildup and modernization of Chinese nuclear weapons and associated delivery platforms, particularly the ballistic missile submarines that have recently demonstrated (after years of technical setbacks) the capability to deploy further out to sea and within striking range of the United States. The next president will have to wrestle with a host of political and military challenges from China, and in the nuclear area, he or she will have to determine how best to deter China without having China further buildup its nuclear arms.

A major issue of concern to China is the potential buildup of U.S. missile defense beyond just a relatively small number of missile interceptors. The ostensible purpose of this very limited U.S. missile defense system is to counter North Korean missiles and Iranian missiles, which are still relatively few in number in terms of longer range missiles. China has been concerned that even a limited or “small” missile defense system could threaten China’s capability to launch a retaliatory nuclear attack against the United States.

In recent weeks, some senators have opened up a debate about whether to remove the word “limited” in the Missile Defense Authorization Act. In particular, Senator Tom Cotton (R-Arkansas) and Senator Kelly Ayotte (R-NH) have taken such action in the Senate Armed Services Committee, while Senator Edward Markey (D-Mass.) has sought to restore the word “limited.” Over the past 20 years, the debate in Congress has shifted, such that there is really no debate about whether the United States should have some strategic missile defense system; instead the debate has been about how much the United States should spend on a limited system and how limited it should be. The next president has an opportunity to renew this debate on first principles: that is, whether a strategic missile system provides some crisis stability, whether this system would impede further nuclear arms reductions, and whether this system could achieve adequate technical effectiveness.

I will save (until a future president’s message) the challenges of Iran and North Korea. For this message, I will close by noting that both the George W. Bush administration and the Barack Obama administration made significant progress in securing and reducing nuclear materials that could be vulnerable to theft by terrorists. Preventing nuclear terrorism is very much a bipartisan issue, as is reducing any and all nuclear dangers. How will the next president build on the tremendous legacies of the two previous presidents in keeping the world’s leaders focused on achieving much better security over nuclear materials? Should the Nuclear Security Summit process be continued? What other cooperative international mechanisms can and should be implemented? As the leader of the world’s superpower, the next president must lead and must cooperate with other leaders in the shared endeavor of making the world safer against nuclear threats. As citizens, let’s encourage the candidates to debate seriously these issues and provide practical plans for reducing nuclear dangers.

I am grateful to all the supporters of FAS and readers of the PIR.


[1] Transcript of September 30, 2014, presidential candidates’ debate at

[2] See:

[3] See:



Three-Dimensional Arms Control: A Thought Experiment

The George W. Bush Administration is not typically viewed as the paragon of arms control. This was the Administration that withdrew from the Anti-Ballistic Missile (ABM) Treaty in 2002, agreed to the Moscow Treaty that same year with no verification provisions, and generally eschewed traditional approaches to arms control, including negotiations and treaties, as Cold War legacies. To be sure, in practice the Administration’s minimal attempts at arms control failed to produce significant results; but in principle, creative and new approaches cannot be so readily discarded. With that in mind, this article is a thought experiment. Some of the proposals suggested here are radical and come with major hurdles, but a non-traditional approach to arms control, based on opportunities rather than challenges, can hopefully generate new thinking.

Read on: View the full version of the article here.


Welcome Back, Multiple Object Kill Vehicles

Ever since the United States began developing a missile defense system, the focus has been on pursuing a robust missile defense system. As not much progress has been made on boost phase interception, it becomes mandatory to study a technology that could make the midcourse system of the ballistic missile more vulnerable to enemy missile defense system. At present, with counter measures like decoys, chaffs, and multiple independently targetable re-entry vehicles (MIRVs), the mid-course phase of the ballistic missile becomes a complicated phase of interception. The Multiple Object Kill Vehicle (MOKV), a program of the United States, is believed to negate these challenges of the missile defense system in the mid-course phase.

Read on: View the full version of the article here.


Nuclear Security and Safety in America: A proposal on illicit trafficking of radioactive material and orphan sources

The special nature of nuclear energy requires particular safety and security conditions and stronger protective measures. The International Atomic Energy Agency (IAEA), as do other international and regional organizations, provides assessment, but it does not know a great deal about the security status of most Member States. It is necessary to learn of and determine the needs and concerns of a State for improving legal framework, reviewing detection of and response to illicit trafficking, and in order to develop a strategic plan that will enhance work that results in tangible improvements of security.

Nuclear law has an international dimension because the risks of nuclear materials do not respect borders. Terrorist acts defy the law; they don’t belong to a State. The possibility of transboundary impacts requires harmonization of policies, programs, and legislation. Several international legal instruments have been adopted in order to codify obligations of States in various fields, which can limit national legislation. There are legal and governmental responsibilities regarding the safe use of radiation sources, radiation protection, the safe management of radioactive waste, and the transportation of radioactive material.

The terrorist attacks of 11 September 2001 represented a clear challenge, but they must not stand as obstacles in the development of nuclear technology. It is necessary to reinforce these efforts in order to improve nuclear energy security, because energy is a vital issue that cannot wait.

Read on: View the full version of the article here.


More From FAS: Highlights and Achievements Throughout Recent Months


In its quest to secure Congressional approval for a new nuclear cruise missile, the Pentagon is putting words in the mouth of President Barack Obama and spinning and overstating requirements and virtues of the weapon. Hans Kristensen, director of the Nuclear Information Project, discusses these false claims and the potential ramifications they could have for the LRSO program. The full post can be viewed here:


In the wake of President Barack Obama’s historic visit to Hiroshima, the first of two Japanese cities destroyed by U.S. nuclear bombs in 1945, the Pentagon has declassified and published updated numbers for the U.S. nuclear weapons stockpile and warhead dismantlements. Kristensen analyzes this data and discusses what it could mean for the Obama administration’s nuclear legacy and the arms control community as a whole, here:


A directive signed by the Director of National Intelligence formally authorizes the use of social media by official investigators who are conducting background investigations for security clearances. The directive was crafted to avoid undue infringements on privacy. Investigators will be limited to considering only publicly available postings. The subjects of a background investigation “shall not be requested or required” to provide passwords for access to non-publicly available materials or to make such materials available; agencies will not be allowed to “friend” an individual for the purposes of gaining access to materials that are not otherwise available; and the consideration of social media must be relevant to the official guidelines for granting access to classified information – that is, they must pertain to substance abuse, criminal conduct, foreign allegiance, or other such criteria. Read Aftergood’s analysis in full here:


The growing prospect of the use of drones for commercial delivery purposes is considered in a new memorandum from the Congressional Research Service. “Can you prevent a drone from flying over your house to deliver a package to your neighbor? Until now, that question has been of purely theoretical interest. However, the Senate recently passed a bill that could significantly change the operational landscape for unmanned aircraft systems (UAS or drones) and make these kinds of hypothetical delivery drones a reality,” the CRS memo begins. Read Aftergood’s take on the debate here:


FAS Visiting Scientist, Dr. David Hafemeister, has just released his new book, Nuclear Proliferation and Terrorism in the Post-9/11 World (Springer 2016), a unique textbook tailored for undergraduate courses on nuclear proliferation and nuclear weapon issues and policy. Read a synopsis of the book, plus an exclusive interview with the author here:


The Obama Administration has famously prosecuted more individuals for unauthorized disclosures of classified information to the media than all of its predecessors combined. But behind the scenes, it appears to have sought administrative penalties for leaks — rather than criminal ones — with equal or greater vigor. “This Administration has been historically active in pursuing prosecution of leakers, and the Intelligence Community fully supports this effort,” said ODNI General Counsel Robert S. Litt in testimony from a closed hearing of the Senate Intelligence Committee in 2012 that was released last week in response to a Freedom of Information Act request. But, he said, “prosecution of unauthorized disclosure cases is often beset with complications, including difficult problems of identifying the leaker, the potential for confirming or revealing even more classified information in a public trial, and graymail by the defense.” Read Aftergood’s analysis in full here:


In light of the 30th Anniversary of the cataclysmic accident at the Chernobyl Nuclear Power Plant, Edward Friedman, Professor Emeritus of Technology Management at Stevens Institute of Technology, takes the opportunity to explore the meaningful lessons learned from that pivotal day in history. Read the full article here:


Leading experts came together to discuss Chernobyl on the eve of its 30th anniversary, the lessons learned, and possible implications that this fateful event has for the nuclear industry today. This special event was convened by the Federation of American Scientists. Speaker presentations and a full recording of the event are available here:


In this op-ed, Tara Drozdenko, Managing Director for Nuclear Policy and Nonproliferation at the Outrider Foundation, examines the science behind the catastrophic accident that occurred on April 26, 1986 at the Chernobyl Nuclear Power Plant in Pripyat, Ukraine, and discusses the lessons learned from that fateful day. Read the full piece here:


In the latest FAS Nuclear Notebook published in the Bulletin of the Atomic Scientists, Norris and Kristensen take the pulse on Russia’s nuclear arsenal, reviewing its strategic modernization programs and the status of its non-strategic nuclear forces. Russia’s non-strategic nuclear forces are currently the subject of much interest in NATO due to concerns that Russian military strategy has been lowering the threshold for when nuclear weapons could potentially be used. Russia has also been increasing operations and exercises with nuclear-capable forces, a trend that can also be seen in NATO and U.S. military posturing. The complete report can be viewed here:


Navy Builds Underground Nuclear Weapons Storage Facility; Seattle Busses Carry Warning

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Seattle busses warn of largest nuclear weapons base. Click image to see full size.

By Hans M. Kristensen

The US Navy has quietly built a new $294 million underground nuclear weapons storage complex at the Strategic Weapons Facility Pacific (SWFPAC), a high-security base in Washington that stores and maintains the Trident II ballistic missiles and their nuclear warheads for the strategic submarine fleet operating in the Pacific Ocean.

The SWFPAC and the eight Ohio-class nuclear-powered ballistic missile submarines (SSBNs) homeported at the adjacent Bangor Submarine Base are located only 20 miles (32 kilometers) from downtown Seattle. The SWFPAC and submarines are thought to store more than 1,300 nuclear warheads with a combined explosive power equivalent to more than 14,000 Hiroshima bombs.

A similar base with six SSBNs is located at Kings Bay in Georgia on the US east coast, which houses the SWFLANT (Strategic Weapons Facility Atlantic) that appears to have a dirt-covered warhead storage facility instead of the underground complex built at SWFPAC. Of the 14 SSBNs in the US strategic submarine fleet, 12 are considered operational with 288 ballistic missiles capable of carrying 2,300 warheads. Normally 8-10 SSBNs are loaded with missiles carrying approximately 1,000 warheads.

To bring public attention to the close proximity of the largest operational nuclear stockpile in the United States, the local peace group Ground Zero Center for Nonviolent Action has bought advertisement space on 14 transit buses. The busses will carry the posters for the next eight weeks. FAS is honored to have assisted the group with information for its campaign. Continue reading

Flawed Pentagon Nuclear Cruise Missile Advocacy

The Pentagon is using flawed arguments to sell a nuclear cruise missile to President Obama?

By Hans M. Kristensen

In its quest to secure Congressional approval for a new nuclear cruise missile, the Pentagon is putting words in the mouth of President Barack Obama and spinning and overstating requirements and virtues of the weapon.

Last month, DOD circulated an anonymous letter to members of Congress after it learned that Senator Dianne Fenstein (D-CA) was planning an amendment to the FY2017 National Defense Authorization Act to put limits on funding and work on the new Long-Range Standoff (LRSO) nuclear air-launched cruise missile. The letter not surprisingly opposes the limits but contains a list of amazingly poor justifications for the new weapon.

The letter follows another letter in March from Under Secretary of Defense Frank Kendall to Senator John McCain that contains false claims about official documents endorsing the LRSO, as well a vague and concerning statements about the mission and purpose of the weapon.

The two letters raise serious questions about DOD’s justifications for the LRSO and Congress’ oversight of the program. Continue reading

Briefing to Arms Control Association Annual Meeting

Click on image to download briefing slides

Yesterday I gave a talk at the Arms Control Association’s annual meeting: Global Nuclear Challenges and Solutions for the Next U.S. President. A full-day and well-attended event that included speeches by many important people, including Ben Rhodes, who is Deputy National Security Advisor for Strategic Communications in the Obama administration.

My presentation was on the panel “Examining the U.S. Nuclear Spending Binge,” which included Mark Cancian from CSIS, Amy Woolf from CRS, and Andrew Weber, the former U.S. Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs. I was asked to speak about the enhancement of nuclear weapons that happens during the nuclear modernization programs and life-extension programs and the implications these improvement might have for strategic stability.

My briefing described enhancement of military capabilities of the B61-12 nuclear bomb, the new air-launched cruise missile (LRSO), and the W76-1 warhead on the Trident submarines. The briefing slides are available here:

Nuclear Modernization, Enhanced Military Capabilities, and Strategic Stability.

This publication was made possible by a grant from the New Land Foundation and Ploughshares Fund. The statements made and views expressed are solely the responsibility of the author.