The United States placed a “naval quarantine” on Cuba, not allowing any more missile shipments to come in. Soviet ships en route to Cuba changed their course away from the quarantine zone.
For thirteen extremely tense days in October, messages between Khrushchev and President Kennedy were exchanged.
Eventually, on October 28, Khrushchev relented, promising that work on missile sites in Cuba would be halted and that the missiles already there would be returned to the Soviet Union. In exchange, Kennedy promised that the United States would never invade Cuba, and that they would withdraw the nuclear-armed missiles they had set up in Turkey. Fidel Castro was furious with this Soviet display of weakness, but could do nothing about it. The Cuban Missile Crisis was the peak of an extremely strenuous relationship between the Soviet Union and the United States, and possibly the main reason for Khrushchev’s fall from power.