AFAIK, their war lay primarily in the Pacific, and beyond supporting the Brits and Russians materially, I’m not really sure why the US would want to involve themselves physically in the European theatre. I do feel fear of Germans beating them to the bomb might have something to do with it, but that’s just conjecture.
i'm not saying they didn't just that they had to fight way fewer than them. if the us were committed to anti-nazi action, they would have actually entered the war before being pressured into. i'm not trying to discount the amount or kind of support the us did give the soviets, i'm just saying that the us had a strategic interest in the soviet union military force being in a state at the end of the war that would be unable to combat the relatively undepleted us allied military force. the us wasn't exactly proactive in combatting nazism...