tough call. Ukraine isn't worth WWIII tho, but I hate seeing people dicked on hard.
We should just let the UN security counsel make the call on this. They won't do anything, and we get to act like we are letting the international community do it's thing.
Regarding our threat to Russia, we should just slap some tarriffs on them and say "There, we told you'd we do something if you invaded Ukraine" and call it a day.