The physical structure of the cold war was put into place at the end of World War II. Winston Churchill, Franklin Delano Roosevelt and Joseph Stalin agreed in Febrary of 1945 at Yalta to divide Germany into four occupation zones. It was agreed that the Soviet Union would have the greatest influence in eastern Europe, where Soviet troops were concentrated. They already occupied Poland, Bulgaria, Romania, Hungary and parts of Czechoslovakia and Yugoslavia, and it would have been difficult to come to an agreement which involved removing these troops. Roosevelt agreed because he had little choice. Finally, it was agreed that independent governments would be established in these lands, and that elections would be free, but the governments would be "friendly to the Soviet Union." This is the beginning of what Winston Churchill would later call the "Iron Curtain" which divided Europe for 45 years.

Truman and Stalin at Potsdam

When the allies met again at Postsdam in July of 1945, relations were more strained. Roosevelt had been replaced by Truman, who was not inclined to humor Stalin once he found out that there had been a successful test of the atomic bomb. America no longer desperately needed Soviet help in the war against Japan. America had halted aid to the Soviet Union because of concerns over Russian behavior in the East.