For the best part of two hundred years people have assumed Russia was washed up and would be a pushover in a war.
Ask Napoleon and Hitler how that worked out for them.
Russia has a nasty habit of turning round and handing out a god-awful smackdown to enemies who have pushed it too far. Trying to oxter the Crimea out of Russian hands would be an absolute red line and insanely foolish.
I don’t like Russia and I am certainly not one of the Putin fan-boys who pop up here regularly but any western intervention in the Ukraine would be a foolish, foolish mistake. If the Ukrainians are that insistent on holding on to Crimea let them fight for it themselves. The rest of us don’t have a dog in that fight.
Not a single GI was involved in pushing the Russians out of Afghanistan. All the Ukrainians need is food, money and equipment.