In 1941 President Roosevelt declared a New World order. The "four liberties" were the right to speak freely, religious freedom, liberty from needs (free trade without any economy barrier) and liberty of fear through disarmament. But Roosevelt could not reach his goals. At the last War conference in Feb.1945 about the liberty order of the three occupying forces President Roosevelt wanted to establish free and democratic voting, but Stalin refused.
26. June 1945 in San Francisco, the United Nations have been founded. Through UN a worldwide peace on earth should be secured. But the reality in Europe and Asia looked differently.
The new elected President Harry S. Truman (1945-1953) made a new Foreign policy. He wanted the containment of Soviet Union, to prevent her expansion. Roosevelt's aim was to give freedom and democracy to the nations after war time. But his foreign expansion didn't work with the Soviets. Therefore Truman chose a different way of foreign politics to contain the Soviet Union.