It's almost a cliche at this point that, no matter what, the USSR will inevitably emerge as a borderline-unstoppable military power. OTL, the Soviets ended WW2 and entered the Cold War as the Red Juggernaut due to being invaded by the Third Reich, and arguably got a boost from WAllied Lend-Lease.
Without that "kick in the pants", would the Soviets develop such a massive war machine?