On October 14, 1962, an American U-2 reconnaissance flight photographed Soviet medium-range nuclear missile launchers being assembled in western Cuba — ninety miles from Florida. The intelligence reached President Kennedy two days later. For the next thirteen days, the United States and the Soviet Union conducted the closest approach to nuclear war the species has yet survived. Khrushchev's gamble was to give Moscow a first-strike capability against the American mainland symmetric to the one Washington had recently installed in Turkey. Kennedy's response — a naval 'quarantine' rather than the air strike his Joint Chiefs demanded — created the time and space for back-channel negotiation that, on the 28th, defused the crisis.
The deal was a quiet reciprocal withdrawal: Soviet missiles out of Cuba, in exchange for a public US pledge not to invade and a private commitment to remove the Jupiter missiles from Turkey. Both leaders had been less in control of their own militaries than they wanted to admit. A Soviet submarine commander, depth-charged by the US Navy and convinced war had begun, came within a single officer's veto of firing a nuclear torpedo. The hotline between Moscow and Washington was installed shortly after, because both sides realized that they had been a phone call away from extinction and did not have the phone.
The crisis is the founding case study of nuclear escalation: how rational actors in symmetrical fear can edge toward catastrophe by small, defensible steps. Every contemporary stand-off — Korea, Iran, Russia–NATO over Ukraine — is read against it.