These vague and unstable resolutions created the foundation for the turmoil that was to come, as Stalin began moving pro-communist governments into Europe one nation after another.
Roosevelt was overconfident that he could negotiate with Stalin. He saw Russia as a conventional imperialist power and Stalin as a man he could do business with. Confident that the differences between him and Stalin could be settled peacefully, he went on vacation in Warm Springs, Georgia. There, on April 12, 1945, he suffered a massive stroke and died. Harry S. Truman succeeded Roosevelt as president, knowing little information with international affairs. Truman, unlike Roosevelt, did not believe Stalin's search for security was rational and viewed the tyrant "with suspicion and even loathing."" On April 23 he met with Soviet Foreign Minister, Molotov, and reprimanded him for violations of the Yalta accords. Molotov was infuriated with Truman and stormed out, leaving Truman with the feeling that Molotov wanted things he should not have. When he met with Stalin in July at Potsdam, they confirmed that Germany would remain divided with Democratic zones in the West and communist zones in the East, and the country would remain that way until the fall of the Soviet empire. As Truman became more informed about Stalin and his plans, he began to associate Stalin with the corrupt people Truman was acquainted with in his past. Truman saw Stalin as a gangster and felt that his requests were unreasonable, and would therefore, not oblige to them. .
By the end of 1945, a fundamental shift had formed a new American policy known as the Containment doctrine. Rather than "attempting to create a unified, open' world, the United States and its allies would work to contain' the threat of further Soviet expansion."" Truman felt that Eastern Europe had to remain open so the countries could elect their own governments.