Following the Cuban Revolution of 1959, bilateral relations deteriorated substantially. In October 1960, the U.S. imposed and subsequently tightened a comprehensive set of restrictions and bans against the Cuban government, ostensibly in retaliation for the nationalization of U.S. corporations' property by Cuba. In 1961, the U.S. severed diplomatic ties with Cuba and engaged in a campaign of terrorist attacks and covert operations in an attempt to bring down the Cuban government. The 1961 Bay of Pigs Invasion, the 1962 Cuban Missile Crisis, and American efforts to stand up to Fidel Castro's attempts to spread communism throughout Latin America and Africa, are main highlights of U.S. antagonism towards Cuba during the Cold War, although Nixon, Ford, Kennedy, and Johnson resorted to back-channel talks with the Cuban government during the Cold War.