
The US President Roosevelt died in 1945. He was replaced by Truman who was strongly anti-Communist and, as the war came to an end, the relationship between America and Russia fell apart.
In 1945, Harry S Truman became president of the USA, determined to confront Communism. He is reported to have told his advisers:
The Russians only understand one language - how many armies have you got? I'm tired of babying the Soviets.
Harry S Truman, 1945
But this was not the only cause of trouble. Historians believed that the wartime alliance between the Soviet Union and America was also wrecked by the huge differences between the two countries in:
The collapse of the wartime alliance led to a Cold War between the two superpowers.