United States wanted to overthrow Fidel Castro because Cuba aligned itself with the Soviet Union. Castro's attacks on U.S. companies and interests in Cuba, his inflammatory anti-American rhetoric, and Cuba's movement toward a closer relationship with the Soviet Union led U.S. officials to conclude that the Cuban leader was a threat to U.S. interests in the Western Hemisphere. And In 1959, Fidel Castro came to power in an armed revolt that overthrew Cuban dictator Fulgencio Batista. The US government distrusted Castro and was wary of his relationship with Nikita Khrushchev, the leader of the Soviet Union.
The USA did not like Castro and refused to trade with Cuba, as a result Castro seized American assets in Cuba and made an alliance with the USSR. President Kennedy tried to overthrow Castro in April 1961. 1,400 Cuban rebels and exiles, with the support of the CIA, launched an invasion of Cuba at the Bay of Pigs.
