Previous - Don't Do Anything (CYOAH)
Stalin knows Himmler's planning to invade the USSR. He decides to attack them first. The declaration of war caught Himmler off guard. The Soviet invasion forces the Germans to dedicate more men to the Eastern front, allowing the British and French to get several victories back in the West.
The war is bloody and drawn out. The Germans are fierce and don't give up, even while on the defensive. Eventually, in 1948, Allied troops march through Berlin, and Himmler is captured and put into Soviet custody. He would later be found dead in his cell, in an apparent suicide. The Japanese weren't as ambitious in their conquests, as they saw the defeat of the Germans. As such, America never joined the war.
The Soviet Union is exhausted from the long war, but Stalin still has plans. Some of his generals say that France is even more worn-out after two major wars and is ripe for conquest. Others think he should focus on rebuilding the nation. Still more feel that he should try to force Germany into joining the USSR. Stalin has to decide.