THAT I am writing this article is largely due to Thomas Schelling. The Nobel Prize-winning economist schooled American governments in how to fight the Cold War without pressing the red button, and destroying the world. As politicians in the 1950s tried to work out how to avoid accidentally destroying the world, a group of economists turned to the recently developed mathematics of games.

Schelling understood the mathematics very well but would modestly explain that he was a user of game theory. By that, he meant he would take seemingly abstract and impenetrable theoretical insights, and turn them into lucid and easily understood arguments. In this way, he played a large role in developing the intellectual climate within which the nuclear superpowers faced off against each for over 25 years, with multilateral disarmament gradually happening.

After reading Schelling’s book, The Strategy of Conflict, Stanley Kubrick turned to Schelling for advice on the plot of Dr Strangelove. While the character of Strangelove is sometimes thought to have been based on the Hungarian mathematician and theoretical physicist John von Neumann, one of the most brilliant thinkers of the 20th century, we see Schelling’s insights throughout the film, especially in imagining the Soviet Union’s ultra-secret “doomsday device”, which would have responded automatically to any nuclear attack by detonating an enormous cobalt bomb and destroying the world.

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In Schelling’s theories, the “doomsday device” gave the Soviet Union a guaranteed second strike capacity. Thinking of two countries possessing nuclear weapons, first strike capacity is the ability to destroy the other country’s weapons before they can be launched, making the nuclear threat ineffective.

Second strike capacity means that a country is still able to launch an attack after the other country has launched its attack. With the “doomsday device” permanently, and irrevocably, armed, ready to explode as soon as it detected a nuclear device exploding somewhere over the Soviet Union, it eliminated the possibility of the US developing a first strike capacity.

This is the key insight of the doctrine of mutually assured destruction. No US government would launch a nuclear attack against a Soviet Union which was certain to destroy it. But nor would the Soviets try to attack the US if the result would be a certain, cataclysmic response. The war should remain cold.

Schelling went well beyond President Kennedy’s claim that in a nuclear war the “fruits of victory are ashes in our mouths”. In his thinking, in any nuclear exchange, there can be no victory for either side.

That makes it possible to “stop worrying, and learn to love the bomb” as the alternative title of Dr Strangelove put it. In a second strike world, no rational government, which trusts its opponent sufficiently, would authorise the use of nuclear weapons.

Between the publication of The Strategy of Conflict and the making of Dr Strangelove, the world had its closest brush with a nuclear war in the Cuban Missile crisis. Neither the US nor the USSR understood the other’s intentions well. In the confusion of this tense stand-off, a loss of nerve by an officer on a single ship could have led to an unfortunate incident, with gradual escalation leading eventually to full-scale nuclear war.

Resolving that crisis required both sides to develop confidence that the other did not seek the annihilation of the other. The removal of missiles from Turkey and Cuba was important, ensuring neither superpower had nuclear weapons close to the other’s strategic command centres.

OPENING new channels of communication was also important. In Dr Strangelove, the USSR keeps its “doomsday device” hidden. In the 1960s, following Schelling’s analysis, the US and the USSR gradually developed a better mutual understanding of their capabilities, and their intentions. That was the foundation for negotiation, with the Anti-Ballistic Missile Treaty of 1972 the first step towards multilateral disarmament.

The treaty was designed to prevent countries being able to defend themselves against a nuclear attack. This effectively ensured that both superpowers would have a second strike capability. They would deploy their arsenal of weapons as a threat to prevent their opponents from using their own weaponry but would not plan to launch their own except in response to being attacked. The acceptance of mutually assured destruction led to the doctrine of no first use. Now, though, it is much more difficult to trust the Russian government. With President Putin’s invasion of Ukraine not progressing to plan, with the Ukrainians proving to be much more capable than expected, and both Europe and the US able to continue to provide it with materiel, Russia has increased the readiness of its nuclear weaponry.

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We see many political leaders, especially France’s President Macron and Germany’s Chancellor Scholz trying to keep lines of communication open. Presumably, the US government still has ways of ensuring messages reach the Kremlin.

Its message must be clear, and unequivocal, re-assuring the Russian government that at present, it has no intention of making Russia’s “special military operation” a reason for declaring war, especially given the effectiveness of the Ukrainian defences.

In this, President Biden needs to play the role of a reluctant but unflinching, warrior. He has to understand that he uses his nuclear weaponry every day – in making the perfectly credible threat of retaliation against Russia’s resort to use of its missiles.

It’s an old idea in modern guise: wanting peace, we prepare for war.