In a stunning move, the Nazis and the Soviet Union signed a non-aggression pact on August 23 1939. The pact which was also known as the Molotov-Ribbentrop Pact, whose terms were kept secret at the time, called for the dividing up of lands between Germany and the Soviet Union. Germany was to receive Western Poland and Lithuania, while the Soviet Union would get Eastern Poland, Estonia, Latvia and Finland.
The Soviets had previously been negotiating with France and Great Britain on a mutual assistance pact. Stalin, however, had lost faith in the British and French ability to deal with the Germans. The Soviets had demanded the right to send troops into Poland in case of a German attack, something that the Poles refused to permit. Thus, no agreement could be reached on mutual defense. The Non-Aggression Pact decisively changed the European balance of power in favor of the Germans.