Before Fidel Castro's revolution, Cuba was led by a corrupt dictator called Batista . Batista's Cuba was under American's control. They were influencing Cuba's political choices, and also controlling their markets and economy.
1959, Fidel Castro started revolution. He kicked out Batista and became the leader of the country.
To show new Cuba's freedom from American control, 1960, he signed a trade agreement with Moscow and received weapons as well. USA threatened Castro by no longer buying their sugar and oil which both are Cuba's valuable export. But USSR bought them instead to save their economy.
USA was upset with Cuban Soviet's relationships, and the send 1400 Cuban exiles to invade and overthrow Castro . The USA mistakenly believed that Castro was unpopular and poorly armed. In April 1961, the Cuban exiles landed at the Bay of Pigs but were easily defeated. Castro had 20000 soldiers supported by Soviet tanks.
USA had put strategic nuclear weapons in Italy and Turkey. Khrushchev wanted to counter this threat by placing nuclear missiles on Cuba - only 90 miles from the USA's eastern coast.
Sep. 1962, Kennedy warned the USSR that he would prevent 'by whatever means necessary' the placement of nuclear weapons on Cuba. Khrushchev gave his word that this would not happen. Oct. 14, a U2 spy plane flew over Cuba and took pictures of missile. Two days later Kennedy was shown the conclusive proof that Khrushchev had broken his word.