The leaders of the victorious countries met once more at Potsdam in July, 1945. Franklin D. Roosevelt, who had died in April, 1945, had been replaced by the Vice-President, Harry S. Truman. While the conference was taking place, the British General Election results were announced. The landslide victory of the Labour Party meant that Clement Attlee replaced Winston Churchill as Britain's main negotiator.
Although Germany had been defeated, the USA and Britain were still at war with Japan. At Yalta, the Allies had attempted to persuade Joseph Stalin to join in the war with Japan. By the time the Potsdam meeting took place, they were having doubts about this strategy. Churchill in particular, were afraid that Soviet involvement would lead to an increase in their influence over countries in the Far East.
At Yalta, Stalin had promised to enter the war with Japan within three months of the defeat of Germany. Originally, it was planned that the conference at Potsdam would confirm this decision. However, since the previous meeting the USA had successfully tested the Atom Bomb. Truman's advisers were urging him to use this bomb on Japan. They also pointed out that its employment would avoid an invasion of Japan and thus save the lives of up to two million American troops.
When Harry S. Truman told Joseph Stalin that the USA had a new powerful bomb he appeared pleased and asked no further questions about it. Truman did not mention that it was a atomic bomb and it appears that Stalin did not initially grasp the significance of this new weapon. However, with the dropping of the Atom Bomb on Hiroshima and Nagasaki in August, 1945, the Japanese quickly surrendered and the Allies were successful in preventing Soviet gains in the Far East.
Stalin's main concern at Potsdam was to obtain economic help for the Soviet Union. Nearly a quarter of Soviet property had been destroyed during the Second World War. This included 31,000 of her factories. Agriculture had also been badly hit and food was being strictly rationed. Joseph Stalin had been told by his advisers that undernourishment of the workforce was causing low-productivity. He believed that the best way to revive the Soviet economy was to obtain massive reparation payments from Germany.
Unlike at Yalta, the Allies were no longer willing to look sympathetically at Stalin's demands. With Germany defeated and the USA now possessing the Atom Bomb, the Allies no longer needed the cooperation of the Soviet Union. Stalin felt betrayed by this change of attitude. He believed that the death of Franklin D. Roosevelt was an important factor in this.
The ending of lend-lease supplies to the Soviet Union immediately the war ended with Germany in May, 1945 and the insistence that Henry Wallace, the US Secretary of Commerce, resign after he made a speech in support of Soviet economic demands, convinced Stalin that the hostility towards the Soviet Union that had been in existence between the wars, had returned.