There are those who claim that Stalin knew war was coming, just not until England fell. This would inevitably bring the U.S. to Great Britain aid. Once sides in question wore themselves out, the "hero" Stalin and his men would swarm down upon Europe like locusts and claim all.
Theories unfortunately is all we have.
BTW....
I too think that going to war with Russia before Great Britain was dealt with, was a catastrophic blunder.