The crisis was over, but naval quarantine continued until the Soviets agreed to withdraw their IL-28 bombers from Cuba, and on November 20, 1962, the United States ended its quarantine. The Us Jupiter missiles were withdrawn from Turkey in April 1963. The United States requested an emergency meeting of the United Nations Security Council on 25 October. U.S. Ambassador to the United Nations Adlai Stevenson confronted Soviet Ambassador Valerian Zorin at an emergency Security Council meeting and asked him to admit the existence of the missiles. Ambassador Zorin refused to answer. The next day, at 22:00 EDT, the United States increased the availability of CS forces at DEFCON 2. At the only confirmed moment in U.S. history, B-52 bombers were constantly put on aerial alert, and B-47 medium bombers were distributed across various military and civilian airfields and ready to take off with 15 minutes` notice.  One-eighth of the 1,436 SAC bombers were in the air, and some 145 intercontinental missiles were ready, some of which targeted Cuba and the Air Defense Command (ADC) moved 161 nuclear-weapon interceptors in 16 dispersal fields in nine hours, with one third maintaining 15-minute alert status.
 23 B-52s armed with nuclear weapons were sent to remote orbits of the Soviet Union to believe that the United States was serious.  Jack J. Catton subsequently estimated that approximately 80 per cent of CS aircraft were ready to take off during the crisis; David A. Burchinal, on the other hand, recalled that a hotline had been set up between the United States and the USSR to prevent such a crisis from happening again. At 1600 EDT, Kennedy recalled EXCOMM members to the White House and ordered that a message be sent immediately to U Thant asking the Soviets to suspend work on the missiles during the negotiations. During the meeting, General Maxwell Taylor announced that the U-2 had been shot down. Kennedy had previously said he would order an attack on such sites if bombed, but decided not to act unless another attack was carried out. Forty years later, McNamara said that while the events at sea were a positive sign of a war that could be avoided, they did nothing to address the missile problem that is already in Cuba. The tense conflict between the superpowers continued during the week, and on October 27, a U.S.
reconnaissance plane was shot down over Cuba and an American invasion force was prepared in Florida. (Commander Rudolf Anderson, 35, pilot of the downed plane, is considered the only American victim of the Cuban missile crisis.) “I thought it was the last Saturday I`d ever see,” recalled U.S. Secretary of Defense Robert McNamara (1916-2009), as quoted by Martin Walker in “The Cold War.” A similar sense of shipwreck was felt by other key players on both sides. In May, Khrushchev and Castro agreed to secretly place strategic nuclear missiles in Cuba. Like Castro, Khrushchev felt that the U.S. invasion of Cuba was imminent and that a loss of Cuba would seriously harm the Communists, especially in Latin America.