Collaboration of the Soviet Union and Nazi Germany during WWII. This documentary film segment will cover the invasion of Poland by the Soviets under Stalin and Germany under Hitler. It will as cover the invasion of Finland by the Soviet Union. "The Soviet Story" (documentary film 2008).

In addition to stipulations of non-aggression, the treaty included a secret protocol that divided territories of Romania, Poland, Lithuania, Latvia, Estonia and Finland into Nazi and Soviet "spheres of influence", anticipating potential "territorial and political rearrangements" of these countries. Thereafter, Germany invaded Poland on 1 September 1939. After the Soviet-Japanese ceasefire agreement took effect on 16 September, Stalin ordered his own invasion of Poland on 17 September. Part of southeastern (Karelia) and Salla region in Finland were annexed by the Soviet Union after the Winter War. This was followed by Soviet annexations of Estonia, Latvia, Lithuania, and parts of Romania (Bessarabia, Northern Bukovina and the Hertza region). It was only in 1989 that the Soviet authorities admitted the existence of the secret protocol of the Nazi-Soviet Pact. A concern about ethnic Ukrainians and Belarusians had been proffered as the reason for the Soviet invasion of Poland, rather than Soviet expansionism (Wikipedia)