<P> In February 1962, Khrushchev learned of the American plans regarding Cuba: a "Cuban project"--approved by the CIA and stipulating the overthrow of the Cuban government in October, possibly involving the American military--and yet one more Kennedy - ordered operation to assassinate Castro . Preparations to install Soviet nuclear missiles in Cuba were undertaken in response . </P> <P> Alarmed, Kennedy considered various reactions, and ultimately responded to the installation of nuclear missiles in Cuba with a naval blockade and presented an ultimatum to the Soviets . Khrushchev backed down from a confrontation, and the Soviet Union removed the missiles in return for an American pledge not to invade Cuba again . Castro later admitted that "I would have agreed to the use of nuclear weapons...we took it for granted that it would become a nuclear war anyway, and that we were going to disappear ." </P> <P> The Cuban Missile Crisis (October--November 1962) brought the world closer to nuclear war than ever before . The aftermath of the crisis led to the first efforts in the nuclear arms race at nuclear disarmament and improving relations, although the Cold War's first arms control agreement, the Antarctic Treaty, had come into force in 1961 . </P> <P> In 1964, Khrushchev's Kremlin colleagues managed to oust him, but allowed him a peaceful retirement . Accused of rudeness and incompetence, he was also credited with ruining Soviet agriculture and bringing the world to the brink of nuclear war . Khrushchev had become an international embarrassment when he authorized construction of the Berlin Wall, a public humiliation for Marxism--Leninism . </P>

What was the peak of the cold war