The Cuban Missile Crisis was a 35-day confrontation between the United States and the Soviet Union, which escalated into an international crisis when American deployments of missiles in Italy and Turkey were matched by Soviet deployments of similar ballistic missiles in Cuba. Despite the short time frame, the Cuban Missile Crisis remains a defining moment in national security and nuclear war preparation. The confrontation is often considered the closest the Cold War came to escalating into a full-scale nuclear war.

In response to the presence of American Jupiter ballistic missiles in Italy and Turkey, the failed Bay of Pigs Invasion of 1961, and Soviet fears of a Cuban drift towards China, Soviet First Secretary Nikita Khrushchev agreed to Cuba's request to place nuclear missiles on the island to deter a future invasion. An agreement was reached during a secret meeting between Khrushchev and Cuban Prime Minister Fidel Castro in July 1962, and construction of a number of missile launch facilities started later that summer.

After several days of tense negotiations, an agreement was reached between the US and the Soviet Union: publicly, the Soviets would dismantle their offensive weapons in Cuba and return them to the Soviet Union, subject to United Nations verification, in exchange for a US public declaration and agreement to not invade Cuba again. Secretly, the United States agreed with the Soviets that it would dismantle all of the Jupiter MRBMs which had been deployed to Turkey against the Soviet Union. There has been debate on whether or not Italy was included in the agreement as well. While the Soviets dismantled their missiles, some Soviet bombers remained in Cuba, and the United States kept the naval quarantine in place until November 20, 1962.

When all offensive missiles and the Ilyushin Il-28 light bombers had been withdrawn from Cuba, the blockade was formally ended on November 20. The negotiations between the United States and the Soviet Union pointed out the necessity of a quick, clear, and direct communication line between the two superpowers. As a result, the Moscow–Washington hotline was established. A series of agreements later reduced US–Soviet tensions for several years, until both parties eventually resumed expanding their nuclear arsenals.