The Molotov-Ribbentrop Pact, also known as the Hitler-Stalin Pact or German-Soviet Non-aggression Pact or Nazi-Soviet Pact and formally known as the Treaty of Non-aggression between Germany and the Union of Soviet Socialist Republics, was a non-aggression treaty between the German Third Reich and the Soviet Union. It was signed in Moscow on August 23, 1939, by the Soviet foreign minister Vyacheslav Molotov and the German foreign minister Joachim von Ribbentrop. The mutual non-aggression treaty lasted until Operation Barbarossa of June 22, 1941, when Nazi Germany invaded the Soviet Union.
Although officially labeled a "non-aggression treaty", the pact included a secret protocol, in which the independent countries of Finland, Estonia, Latvia, Lithuania, Poland and Romania were divided into spheres of interest of the parties. The secret protocol explicitly assumed "territorial and political rearrangements" in the areas of these countries.
Subsequently all the mentioned countries were invaded, occupied or forced to cede part of their territory by either the Soviet Union, Germany, or both.