Oh come on, let's get real. Nazis, or Soviets are not some mythical creatures that was summoned by the Hitler and Stalin to do their bidding - they are regular people, who decided that not to intervene even when they knew that what's going on around them is wrong!

Soviets butchered their own people, Czars, and launched multiple wars against neighboring countries. They were aggressors, and not only during the world war 2, but before and after as well. Plain and simple.