The United Nations was formed on October 24, 1945, to keep peace between countries in the world. However, the relationship between the Western Allies and the Soviet Union had worsened during the war and, soon after the war, each power quickly built up their power over the controlled area. In Western Europe and West Germany, it was the United States, while in East Germany and Eastern Europe, it was the Soviet Union, in which many countries were turned into Communist states. The Cold War started after the formation of the American-led NATO and the Soviet-led Warsaw Pact.