Participating in a multilateral civil war is much easier than actually invading a unified country, because you have friendly forces to get you in past the frontier and help your supply lines out. Generally speaking invading armies haven’t had a great time in Russia when there wasn’t a civil war on. America on the other hand is an absolute nightmare to consider invading, given geography and the power of our navy.

The Bolsheviks were absolutely correct to be paranoid about the west’s intent towards them. But that doesn’t mean that American tanks rolling east through the Fulda gap was that likely either. Too bloody, and too likely to fail.