In 1955, ten years after Robert Oppenheimer, Leslie Groves, and the 130,000 workers of the Manhattan Project built the first atomic bomb, the United States had 2,400 and Russia had 200. At present, the USA has over 3,000, Russia has over 4,000, and China is building an arsenal of hundreds. Most of these are hydrogen bombs many times more powerful than the bombs dropped on Hiroshima and Nagasaki. These modern arsenals no longer require a bomber plane to deliver them — ICBMs can throw bombs around the earth in half an hour. When we sleep, we sleep as targets of nuclear weapons.

A global thermonuclear war would be the most horrifying event to happen in humanity’s history. If cities were targeted, at the very least, tens of millions would instantly die just like the victims of Hiroshima and Nagasaki. Survivors described the scenes of those explosions as “just like Hell” and “burning as if scorching Heaven.”

Afterwards, hundreds of millions could starve due to economic collapse. It’s also possible the ozone layer would be damaged for years and temperatures would drop us into a nuclear winter. In the worst case scenario, this would render the northern hemisphere uninhabitable for years, causing an existential catastrophe.

Faced with this possible future, why don’t we agree it’s too horrible to allow and find a way to disarm? Since the invention of nuclear weapons, there have been efforts to push nuclear states to disarm, both for moral and practical reasons. Intuitively, this also makes sense: why do we leave ourselves open to the possibility of nuclear war, of which Ronald Reagan and Mikhail Gorbachev once said “cannot be won and must never be fought?”

However, now that we’re in this situation, it isn’t easy to leave it. 

Why can’t we disarm?

Various forces make disarmament appear intractable — even when international relations aren’t as frayed as they are today! For one, states are not rational unitary actors. They contain many different stakeholders with different interests:

  • National leaders feel the need to signal strength to various constituents and don’t want to lose elections for seeming weak on national security.

  • Defence contractors seek profits for their shareholders.

  • Bureaucratic inertia preserves the status quo.

  • Inter-service rivalries (e.g. between the Navy and Air Force) lead to new rationalisations of weapon systems.

  • Members of Congress feel that weapon systems provide value to their voters — including jobs!

  • Nuclear weapons can provide a sense of prestige and national glory.

Moreover, nuclear weapons serve a variety of important roles for states, including:

  • Deterring against nuclear war
  • Deterring against conventional war
  • Deterring against other strategic threats (e.g. biological weapons)
  • Balancing actual or perceived strategic imbalances
    • For example, during the Cold War, the US partly saw its nuclear arsenal as a defence against the possibility of the Soviet Union invading Europe.
  • Signalling credible defence commitments to partners and allies
  • Providing bargaining power in international negotiations and providing the power to compel other states

But even if stakeholders were aligned and a great power was willing to disarm, it’s possible that disarmament could increase the risk of a global catastrophe. Disarmament could destabilise what some experts call “strategic stability.”

What is strategic stability?

All the definitions are hotly contested, but one definition is a situation in which great powers are disincentivized to use nuclear weapons (or, more broadly, military coercion) against each other. This is arguably the reason for the lack of major wars since WWII (the Long Peace and New Peace).

We didn’t always have strategic stability. When the USSR was new to nukes — and suddenly the world had two nuclear powers — the situation felt very unstable for those involved, and the calculus of war leaned much closer to offence. Even Bertrand Russell, the philosopher and renowned pacifist, suggested a preemptive strike on the USSR in order to get through an inevitable war more quickly. Simultaneously, in 1954, Soviet officers debated preemptive war — there was a shared belief that a nuclear war “would destroy capitalism but allow communism to flourish.”1

But the world crawled toward strategic stability. The US’ initial nuclear deterrent was to always have nuclear bombers in the air, ready to respond to attack. Since this initial system, countries have achieved stability by developing more survivable systems: hardened silos, better launch detection, near-undiscoverable nuclear submarines, and combinations of different launch structures (nuclear triads).

What is strategic stability made out of? The assurance on both sides that an attack will be responded to with force. This is achieved by launch on warning or second-strike capability

“Launch on warning” means the launch of nuclear weapons if early detection systems spot an incoming attack. This is Russia’s official policy. It is unclear if China is moving some of its nuclear force from a second-strike policy to a launch-on-warning policy. 

“Second-strike capability” means that even if a country is devastated by a nuclear attack, their nuclear forces are robust enough to survive and guarantee a response — this is the official policy of the US2 (though it can launch on warning). For example, if Russia destroyed the US’ nuclear silos, the US could still counter with its submarine and bomber forces, the other two legs of its nuclear triad.

Even though Russia and the US have different policies for responding to nuclear attacks, we nonetheless find ourselves in strategic stability — a situation sometimes referred to as “mutually assured destruction,” but for each side just looks like effective deterrence.

Why strategic stability isn’t perfect

“To invent the sailing ship or the steamer is to invent the shipwreck.” – Paul Virilio

Even if we have strategic stability, we have to worry about:

  1. Accidents: We have a worrying history of near-misses. Detection systems aren’t perfect, and humans end up needing to make judgement calls. So far, we’ve been quite lucky, such as when a Soviet commander happened to be in the right position to veto the use of a nuclear torpedo during a misunderstanding in the Cuban Missile Crisis.

  2. Misunderstandings and unintended escalation: Major nuclear powers can have different understandings of fundamental concepts like “strategic stability” and “mutual vulnerability.”3 In a crisis, one power may unwittingly cross another’s red lines, triggering nuclear escalation.

  3. Irrational actors: Strategic stability depends on rational actors. But sometimes actors aren’t rational! In fact, they may even act irrationally in order to further their goals, as Nixon did when he threatened nuclear weapon use in Vietnam. 

  4. The escalation of regional conflicts: Sometimes things just spiral out of control, and each individual step feels correct even though the path leads to disaster in the end.

  5. Innovations that destroy strategic stability and make a pre-emptive strike tempting again: Strategic stability could be disrupted technologically by innovations that give an upper hand to one party. This incentivizes the other party to strike first before losing capability. Possible future innovations include:

    1. Advances in space-based weapon systems like fractional orbital bombardment systems

    2. Advances in artificial intelligence4

    3. Entanglement of nuclear and non-nuclear systems 

    4. Other threats to nuclear command, control, and communications (NC3) systems, including advanced cyber operations

For these reasons, we can’t rest easy. It isn’t a perfect system, and over a long enough period of time, we will slip up. My colleague Luisa Rodriguez estimated the annual probability of nuclear war at 1.17%. For a child born today that’s a 60% probability across their lifetime. Without something changing, it’s a long game of Russian Roulette: Whatever the probability, all it takes to lose is more rounds. 

This is why disarmament or reinforcements to strategic stability can’t be abandoned as a goals, even without a clear path forward. And with a little luck, what was a possibility far off in the horizon can sometimes fall into arm’s reach.

What we can do

There are still things we can do in the meantime to improve our situation. 

  • Preventing great power conflict: This includes preventing regional conflicts from escalating. Most nuclear risk seems to be concentrated in times of heightened tension — there were plenty of near-misses during the Cuban Missile Crisis, but only one has been recorded since the collapse of the Soviet Union, for example.

  • Improving our understanding: There are important questions we still lack clarity on, like whether nuclear winter is a real concern. Furthermore, we’re entering a new nuclear era with important unknowns, like what changes in deterrence once there are three nuclear superpowers. Answering this question is highly recommended by Founders’ Pledge.

  • Work on “right-of-boom” philanthropy: Nuclear security philanthropy has focused overwhelmingly on prevention, “left of” the theoretical first nuclear use, taking it as a given that global thermonuclear war comes next. This means that work on what happens after the first nuclear use has been quite neglected in philanthropy, presenting opportunities for philanthropic intervention.

  • Other options listed in our problem profile on nuclear security.

Nuclear security is an odd existential risk: it is non-neglected insofar as states take it seriously, but nuclear philanthropy is at a historic low and the talent pool of qualified experts is shrinking. Nuclear risks are concrete, present, and massive, but meaningful paths to reducing them seem intractable. Because of this, we still need people to go looking for creative solutions (and you can learn more about policy skills and research skills in our articles). If our descendents can sleep without fear of destruction at the press of a button, we’ll have accomplished something great. 

Enter your email and we’ll mail you a book (for free).

Join our newsletter and we’ll send you a free copy of The Precipice — a book by philosopher Toby Ord about how to tackle the greatest threats facing humanity. Many of our readers have found it helpful for deciding on their careers.


With thanks to Carl Robichaud and Amy Woolf for their thoughts, and Christian Ruhl for his feedback on this post

    Notes and references

    1. “On March 12 Malenkov in a public speech … [described] nuclear war as an unmitigated catastrophe that must be avoided at any cost―a view at variance with the still prevailing Soviet position that such a war would destroy capitalism but allow communism to flourish” – Page 53 of pdf

    2. “…while the United States maintains the capability to launch nuclear forces under conditions of an ongoing nuclear attack, it does not rely on a launch-under-attack policy to ensure a credible response. Rather, U.S. nuclear forces are postured to withstand an initial attack.” 2022 National Defense Strategy of the United States of America

    3. “US participants wanted to be certain that China understood what was meant when they used terms like “transparency,” strategic stability,” and “deterrence.” It soon became clear that there were differences of interpretation.” A report from Pacific Forum

    4. A RAND report argued that “It seems reasonable that such a capability, at least for some aspects of the decision making process, could be achieved by 2040 given the progress AI is making in increasingly complex and poorly specified tasks.”