The Increasing Peril of Nuclear Weapons: And how physicists can help reduce the threat

By Stewart Prager, Steve Fetter, Alex Glaser, Zia Mian, Sébastien Philippe, and Frank von Hippel

It is poignant to be writing about nuclear weapons in the midst of the coronavirus crisis. We were caught unprepared for the pandemic. The last pandemic of the scale of covid-19 occurred 100 years ago. The only two nuclear explosions in conflict occurred in Japan 75 years ago. There is no preparation for nuclear war. It is urgent to increase drastically efforts to avoid a second, more destructive use of nuclear weapons. To this end, the APS has initiated a project through its new Innovation Fund to engage the US physics community in advocacy for steps toward nuclear risk reduction.

The virus and nuclear weapons share some properties, but the difference in scale and risk is immense. Both start from a chain reaction. The viral chain reaction of infection can, if unchecked, kill millions worldwide in months and overwhelm health care systems. The neutron-induced fission chain reaction can fission about a kilogram of plutonium in one microsecond. When multiplied by a second fusion-fission explosive, and delivered by thousands of warheads, it can kill hundreds of millions directly, and billions indirectly. Any health care systems not destroyed would barely function, offering mostly palliative care.

The nuclear threat is clear. Controlled by a handful of men in nine nations, the current world military stockpile of more than 9,000 warheads can release about 300,000 times more explosive energy than that of the Hiroshima bomb, which claimed more than 100,000 lives. A fraction of this current nuclear arsenal could eliminate civilized life many times over.

Today, Russia and the US have about 2,000 nuclear warheads ready to launch within minutes of receiving a command. The decades of the bipolar nuclear standoff between the two nations saw numerous crises, close calls, and false warnings of attack that narrowly avoided causing a mistaken retaliatory nuclear launch. Former head of US Strategic Command, General Lee Butler concluded: “We escaped the cold war without a nuclear holocaust by some combination of skill, luck, and divine intervention, and I suspect the latter in greatest proportion.”

Any false comfort derived from 75 years of nonuse should be avoided. As former Secretary of Defense William Perry noted in 2015: “Today, the danger of some sort of a nuclear catastrophe is greater than it was during the Cold War and most people are blissfully unaware.” The danger of nuclear use has indeed increased through at least five developments:

Stewart Prager

Stewart Prager

Steve Fetter

Steve Fetter

Alex Glaser

Alex Glaser

Zia Mian

Zia Mian

Sebastien Philippe

Sébastien Philippe

Frank von Hippel

Frank von Hippel

  1. The collapse of arms control: Throughout the decades of rivalry between the US and the USSR (and later Russia), arms control helped restrain arsenals, costs and misinformation. A foundation was provided by the 1972 Anti-ballistic Missile (ABM) Treaty, which limited defenses in order to avoid provoking offensive weapon build-ups. This facilitated the removal of thousands of warheads from service. The 1987 Intermediate Nuclear Forces (INF) Treaty eliminated about 6,000 nuclear warheads that faced each other in the Soviet Union and Western Europe. Long-range, strategic weapons were reduced from a high of over 60,000 warheads in the mid-1980’s to today’s much reduced arsenals by a series of agreements, most recently the New START Treaty signed in 2011.

    Unfortunately, the US withdrew from the ABM treaty in 2002 and from the INF treaty in 2019, and the current Administration is inclined to let the New START Treaty lapse, without renewal, in February 2021. The potential demise of New START would leave Russia and the US with no constraint on long-range nuclear weapons for the first time in 50 years. The absence of inspections and verification provided by the treaty would feed worst-case projections of each adversary’s weapon system capabilities.

    More recently, a group of Senators asked for the United States to “un-sign” the Comprehensive Test Ban Treaty so as to enable a nuclear weapon test, and in May 2020 senior US officials considered such a test, the first since 1992. The Senate Armed Services Committee has authorized $10 million to speed any possible test, which might take 6 to 10 months to arrange, opening the door for tests by other nuclear weapon states.

  2. A new arms race: The escalatory response and counter-response dynamic of an arms race is underway, but this time involving three countries. The United States is beginning a 30-year, trillion-dollar replacement and upgrade of essentially all its nuclear weapons and delivery capabilities with next-generation systems. To evade future US military defenses Russia is developing hypersonic reentry vehicles that can maneuver in the upper atmosphere, underwater nuclear torpedoes, and ICBMs that can fly over the South Pole. China is building up its relatively small arsenal of strategic ballistic missiles and developing hypersonic reentry vehicles, also, at least in part, in response to the US build-up of missile defenses. The US is developing some of the same weapons and is redoubling its commitment to missile defense.

  3. Proliferation and alliances: An increasingly complex and tangled web of cooperation and conflict links the nine states that now have nuclear weapons: the US, Russia, the UK, France, China, Israel, India, Pakistan, and North Korea. Decision makers in these countries may have competing ambitions and commitments. This yields numerous possible scenarios for intentional conflict, accident or miscalculation. In large part, because of the Non-Proliferation Treaty the number of nations with nuclear weapons has increased by only one, North Korea, since the end of the Cold War. It could have been even worse and may become so.

  4. Cyber-technology: The rapidly developing capabilities of cyberwarfare can undermine strategic stability. Catastrophe could ensue if a successful cyberattack on nuclear command and control could mimic a nuclear attack by an adversary, send a counterfeit order to launch a nuclear missile, or sever communications between a nation’s leader and the military during a nuclear crisis.

  5. Non-state actors: The global stock of weapons-usable material (roughly 1,800 tons of highly enriched uranium and plutonium), sufficient for more than 100,000 bombs, is a potent target for theft by non-state actors or terrorists.

Nonetheless, past progress and success in nuclear arms control demonstrates that this problem can be solved. The 1970 Nuclear Non-Proliferation Treaty provides a critical foundation for the control and elimination of nuclear weapons. Five nuclear weapon states (the US, Russia, UK, France, and China) are parties and have committed to “cessation of the nuclear arms race at an early date and to nuclear disarmament.” India, Pakistan, Israel, and North Korea are not members, but have all indicated in their own way that nuclear disarmament is possible in principle. The absence of meaningful progress towards nuclear disarmament, however, is threatening the durability of this critical treaty.

Meanwhile, the other 184 member states of the United Nations have forsworn nuclear weapons. Six multinational treaties have established regions of the globe, including the continents of Africa and South America, to be nuclear-weapon-free zones. The 2017 United Nations Treaty for the Prohibition of Nuclear Weapons commands the support of a large fraction of the world’s non-weapon states.

Physicists have played a powerful role in arms control. Early on they issued prescient warnings of the catastrophic harm to civilians and cities from nuclear explosions, the dangers of a nuclear arms race, and the genocidal potential of thermonuclear weapons. Later physicists informed opposition to the placement of nuclear-tipped defensive missiles near US cities in the 1970s and to the unfeasible Strategic Defense Initiative in the 1980s. They worked constructively to advance new ideas for arms control, dialogue and cooperative security to help end the Cold War.

Three decades on, the issue of nuclear arms has fallen off the radars of both the physics community and the broader public. The debate has fallen into the hands of vested interests and insiders. We believe, however, that if re-engaged, the physics community could again be an influential voice in informing the public, Congress, and other key stakeholders of the necessity and possibilities of nuclear risk reduction.

For this purpose, we have joined with other concerned physicists from a handful of universities and other organizations across the country to build a Physicists Coalition for Nuclear Threat Reduction ( The goal of this project over the next two years is to establish a network of citizen-scientists committed to understanding and advocating for nuclear threat reduction. The Coalition welcomes all physical scientists, including those working within engineering science.

The Coalition is supported by the APS and the Carnegie Corporation, is partnered with the APS Office of Government Affairs, and is managed through Princeton University’s Program on Science and Global Security.

We plan to inform US physicists on nuclear threats and possible threat-reduction measures, recruit interested scientists into the coalition, and help them connect to the public debate and policy process. As a first step, experts on nuclear arms issues will carry the messages directly to physicists in universities, at professional meetings and conferences, in national laboratories, and in industry. Institutions interested in arranging for a colloquium speaker on nuclear arms issues can do so at

For those physicists who are interested in becoming active, we will facilitate their efforts to educate members of Congress and others on nuclear policy issues. There are numerous policies the United States can implement to reduce nuclear-weapon risks and which could be possible foci of advocacy by the Coalition. These include extending the New START Treaty, adopting a sole-purpose or no-first-use posture, abandoning the launch-on-warning option and the destabilizing silo-based ballistic leg of the triad, and re-establishing limits on missile defense systems. Unlike the battle against a pandemic or climate change, the threat of nuclear weapons is not a fight with nature. All that is required is societal education and will. Physicists can be a powerful force to help build the former and instill the latter. During this critical time, we should seize the opportunity.

The authors are among the founding members of the Physicists Coalition for Nuclear Threat Reduction. Stewart Prager, Alex Glaser, Zia Mian, Sébastien Philippe, and Frank von Hippel are at Princeton University. Steve Fetter is at the University of Maryland.

APS encourages the redistribution of the materials included in this newspaper provided that attribution to the source is noted and the materials are not truncated or changed.

Editor: David Voss
Staff Science Writer: Leah Poffenberger
Contributing Correspondent: Alaina G. Levine
Publication Designer and Production: Nancy Bennett-Karasik

July/August 2020 (Volume 29, Number 7)

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APS Responds to COVID-19: Activities to Assist Graduate Students
APS Responds to White House Proclamation on Visas
From Passion to Action: Levers & Tools for Making Physics Inclusive & Equitable
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The Division of Fluid Dynamics
International Exchanges During COVID-19
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Learning Assistants at Arizona State University Help Virtual Classrooms Stay on Track
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