The Soviet Union was established in 1917, they raced to prepare for WW2. They were the actual primary target for Germany's Lebensraum. Their options resistance or annihilation. The U.S. and European allies couldn't have won the war without the Soviet Union, the Soviet Union couldn't have won without Western assistance. What's telling, after Germany was defeated, the West immediately turned around and began preparing to fight the Soviet Union. They even went so far as to employ Nazis under "Operation Gladio." Western Germany did some really weird stuff under their rule, like housing orphans with pedophiles to "rehabilitate" them.