The only way for America to effectively fight this new battle with Russia is economically. The U.S. still stands on very solid financial ground, especially compared to the Russians. Theirs is a much more volatile and vulnerable market. American treasury bonds are still one of the safest investments in the world, while Russia is already feeling the effects of U.S. and EU sanctions.
If Ukraine wants to go to war with their noisy neighbor, they are within their right and the U.S. should support them with everything short of boots on the ground or planes in the air. This war, in the more literal sense, is one for Ukraine and the EU to fight, not for the U.S.
Are there instances where the U.S. should send troops into Europe? Yes, but we are so far away from that at this stage.