Why was Khrushchev doing this?
NATO had military bases in Turkey, only a short distance from the Soviet Union - Khrushchev wanted the USA to understand how it feels to be under threat
The Berlin wall was presented as a failure for Khrushchev by many soviet critics. If he could outwit Kennedy over Cuba it would help to restore his reputation
Khrushchev may have feared another American attack. If the Americans overthrew Castro, it would be another defeat for communism.