The Cold War was a period of intense political rivalry between the United States and the Soviet Union. It was a war in name only, since no fighting took place between the two sides. Nevertheless, there were several occasions when aggressive actions by the Soviets contributed to the political tensions of the Cold War. These include the Soviet invasion of Hungary in 1956, the Berlin Crisis of 1961, the Cuban Missile Crisis of 1962 and the invasion of Czechoslovakia in 1968.

Hungarian Uprising

Hungary was one of a number of Eastern European countries that had communist governments closely aligned with the policies of the Soviet Union. In October 1956, a group of Hungarian students sparked a popular uprising against the communists. The uprising was successful, and on November 1 the country's new pro-democracy government announced its intention to break all ties with the Soviet Union. Three days later the Soviet Army sent its tanks into the Hungarian capital of Budapest. The new government was deposed, thousands of civilians were killed and the communist government was restored.

The Berlin Wall

Berlin, the capital city of Germany, lay inside the communist-controlled eastern sector of the country. Within the city itself, however, only East Berlin was controlled by the Soviet Union. West Berlin was under the joint control of the United States, Britain and France. The Soviet leader Nikita Khrushchev disliked this enclave of democracy deep inside communist territory, so he tried to persuade the Western allies to vacate the city. When they refused to do so, Khrushchev arranged to have a concrete wall built around the entire perimeter of West Berlin. The Berlin Wall remained in place from August 1961 until November 1989.

Cuban Missile Crisis

In October 1962, U.S. aerial reconnaissance photographs revealed the presence of Soviet medium-range nuclear missiles on the island of Cuba. These weapons were within easy striking distance of the eastern seaboard of the United States. After initially denying that any Soviet missiles were stationed in Cuba, Khrushchev claimed that they had been put there to deter the U.S. from invading the island. After two weeks of tense negotiations, the Soviets agreed to remove the missiles from Cuba in return for a number of concessions by the United States.

Prague Spring

In the Spring of 1968, Alexander Dubcek became the new leader of Czechoslovakia. Dubcek was a member of the Communist Party, but he had leanings toward Western-style democracy. He embarked on a program of reforms aimed at democratizing the communist system. This program, referred to as the Prague Spring, was welcomed in the West but viewed with alarm by the Soviet Union. By the Summer of 1968, the Soviets felt they had to take military action. On August 20 an invasion force of half a million troops entered Czechoslovakia and forced Dubcek's government to reverse all its reforms.