re: What would a U.S.-Russia war look like?

The Russian conventional military would get waxed by any of the major western European powers, including the much-maligned France. They'd have a tough time with Poland, and while they'd beat Ukraine, it wouldn't be a walkover. The Russian army is a shadow of the Soviet era, and even then it was largely a hollow force.

If it went nuclear, all bets would ge off.