A day earlier, in a televised speech Kennedy announced that U.S. spy planes had discovered Soviet missile bases in Cuba. These missile sites—under construction but nearing completion—housed medium-range missiles capable of striking a number of major cities in the United States, including Washington, D.C. Kennedy announced that he was ordering a naval “quarantine” of Cuba to prevent Soviet ships from transporting any more offensive weapons to the island and explained that the United States would not tolerate the existence of the missile sites currently in place. The president made it clear that America would not stop short of military action to end what he called a “clandestine, reckless and provocative threat to world peace.”
What is known as the Cuban Missile Crisis actually began on October 14, 1962 — the day that U.S. intelligence personnel analyzing U-2 spy plane data discovered that the Soviets were building medium-range missile sites in Cuba. The next day, President Kennedy secretly convened an emergency meeting of his senior military, political, and diplomatic advisers to discuss the ominous development. The group became known as ExCom, short for Executive Committee. After rejecting a surgical air strike against the missile sites, ExCom decided on a naval quarantine and a demand that the bases be dismantled and missiles removed. On the night of October 22, Kennedy went on national television to announce his decision. During the next six days, the crisis escalated to a breaking point as the world tottered on the brink of nuclear war between the two superpowers.
After several days of tense negotiations, an agreement was reached between Kennedy and Khrushchev. 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 avoid invading Cuba again. Secretly, the United States agreed that it would dismantle all US-built Jupiter MRBMs, which had been deployed in Turkey against the Soviet Union; there has been debate on whether or not Italy was included in the agreement as well.
When all offensive missiles and light bombers had been withdrawn from Cuba, the blockade was formally ended on November 21, 1962. 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 began to build their nuclear arsenals even further.