The Cold War was the time of rivalry and conflict between the USA and the Soviet Union. It started at the end of World War II and ended with the collapse of communism at the end of the 1980s. It was a time of political tension, in which both superpowers tried to prevent each other from gaining too much power. Even if the conflict did not result in a real war, there were many situations in which the world was very close to it. After World War II Although the United States and the Soviet Union were allies during World War II, they had different ideas about the future of the world. At the end of the war the Soviets controlled much of Eastern Europe and installed Communist governments there. The United States, on the other side, wanted to stop Communist ideas from spreading. It helped Western European countries to stay free and also gave them big sums of money to help rebuild their weak economies. The border between the Communist east and the free west was called the Iron Curtain and ran straight through the middle of Europe. Military Blocs after World War II After World War II two military organizations emerged. In 1949 the United States and other western countries founded NATO (the North Atlantic Treaty Organization), on the other side the Soviets led the Warsaw Pact, a military organization of eastern European countries. Both military blocs wanted to defend themselves in case the other attacked. Berlin Two of the major events of the Cold War took place in Berlin. After World War II the city was divided into four zones. The French, British and American zone became West Berlin and the Soviet zone became East Berlin. When the Soviets tried to cut off supply routes to the city the Americans reacted by airlifting food, clothes and other supplies to Berlin to help the city survive. In the 1950s many East Berliners moved to West Berlin to escape Communism. The East German government had no way of stopping them. During this decade thousands of people crossed the border to freedom. In 1961 the East German government erected a wall around Berlin. It became the most famous symbol of the Cold War. Cuba Another political and military showdown took place in Cuba. In 1959 rebel leader Fidel Castro overthrew western leaders and installed a Communist government on the island. Soon, the Soviet Union sent supplies and weapons to support Cuba. In 1962 the Soviet Union set up nuclear missiles on the island. To the Americans, nuclear missiles 90 miles from the coast of Florida were an unacceptable threat to their safety. After days of conflict and tension the Soviets finally agreed to remove their weapons from Cuba. Other Cold War events The Cold War spread to other parts of the world as well. The Soviet Union tried to expand their influence to Asian countries. Mao Zedong became the first communist leader in China in 1949. The Chinese nationalists were driven off the mainland to Taiwan. In the years that followed, however, China challenged the Soviet leadership in the Communist world. After World War II the Soviets occupied the northern part of Korea and set up a Communist government there. When North Korean forces invaded the south in 1950s, the United States led allied forces against the Communist north. After three years of fighting the Korean War came to an end. The peninsula was divided into North and South Korea.