It marked Recording the 50th anniversary Social_event of the Molotov–Ribbentrop Pact between the Soviet Union and Nazi Germany .

The German invasion began Process_start on 1 September 1939 , one week after the signing Sign_agreement of the Molotov–Ribbentrop Pact between Germany and the Soviet Union .

On 17 September , the Soviet Red Army invaded Attack Eastern Poland , the territory beyond the so-called Curzon Line that fell into the Soviet `` sphere of influence '' according to the secret protocol of the Molotov–Ribbentrop Pact ; this rendered Supply the Polish plan of defence Defending obsolete .

The Soviet ( as well as German ) invasion Attack of Poland was indirectly indicated Statement in the `` secret additional protocol '' of the Molotov–Ribbentrop Pact signed on Sign_agreement 23 August 1939 , which approximately divided Poland into `` spheres of influence '' of the two powers and questioned the future existence Presence of the Polish state .

An agreement at the Yalta Conference permitted Agree_or_refuse_to_act the Soviet Union to annex almost all of their Molotov–Ribbentrop Pact portion of the Second Polish Republic , compensating Supply the Polish People 's Republic with the greater southern part of East Prussia and territories east of the Oder–Neisse line .

Many sources conclude Coming_to_believe that the Soviet Union had intended to conquer all of Finland , and use Using the establishment of the puppet Finnish Communist government and the Molotov–Ribbentrop Pact 's secret protocols as evidence of this , while other sources argue Agree_or_refuse_to_act against the idea of the full Soviet conquest .