Russia actually teamed up with German Nazis to attack Poland in 1939 (The Molotov–Ribbentrop Pact).
I am realizing that many younger folks in the West and Global South (and Asia) don't know this part of Eastern European history: Russia did fight the German Nazis, but not right away. Russia actually teamed up with German Nazis to attack Poland in 1939 (The Molotov–Ribbentrop Pact). Russia only turned against Germany in 1941 when Germany attacked it (Operation Barbarossa). However, German Nazis modeled many of their genocidal policies (concentration camps, medical experiments on prisoners, mass deportations) on Stalin's policies implemented long before WWII within the Soviet Union on its own ethnic groups. Modern scholars estimate that Stalin killed between 6 to 9 mln of his own people. However, right around the Fall of the Berlin Wall, Russian media reported that Stalin might have killed as many as 20 mln of his own people....Here's an archival article in NYT from 1989, which speaks about it (so much hope back then about Russia taking responsibility for its past...):