The Cuban Missile Crisis, which lasted for 13 days in October 1962, is seen by many pundits as the closest the United States and the Soviet Union came to all-out nuclear war. The Soviets were unhappy that the Americans were deploying nuclear missiles in Italy and Turkey. They retaliated by siting nuclear weapons on Cuba, just 90 miles from Florida.
After that, the United States blockaded Cuba to prevent delivery of more missiles and demanded that the Russians withdraw the missiles they’d already deployed. Much to the relief of a terrified world, presidents Kennedy and Khrushchev hammered out a deal. The result was Soviet nuclear weapons were removed from Cuba, and U.S. missiles were withdrawn from Turkey.