The world came closest to nuclear war during the Cuban Missile Crisis. We find that there existed two paths by which nuclear war might have occurred. The first path involves unrestrained hard-liners. Nuclear weapons did not deter some actors from proposing escalatory actions, including the use of nuclear weapons. Luckily, both Kennedy and Khrushchev reined in their respective hard-liners. Along the second path, situations – not known at the time – could have led to an initial use of nuclear weapons, after which events might have spiraled out of control. The US, for example, did not know that the Soviets had placed tactical nuclear weapons in Cuba. If the US had tried to invade Cuba to topple Castro – as some people advocated – then the Soviets might have used the weapons. Ultimately, Kennedy successfully used a quarantine and threatened force to compel the Soviets to withdraw their missiles from Cuba. The threat of nuclear war lingered behind these actions. In the end, however, the crisis ended not because of nuclear deterrence but rather because both sides reached a mutually acceptable bargain. Kennedy promised not to invade Cuba and to remove US missiles from Turkey; Khrushchev, meanwhile, agreed to remove Soviet missiles from Cuba.