I disagree with you and Chris that Ukraine is of de minimus strategic importance to the United States.
My focus is on the will of the Ukraine people, who have increasingly demonstrated that they are committed to the West, committed to democracy, opposed to autocratic oppression. We have to defend that energy. We have to walk the walk.
Putin is a very calculated person. He assumed that America, having just withdrawn from Afghanistan in clusterfuck fashion, lacked the wherewithal to push back on Putin’s aggression (and obsession) re Ukraine. Putin assumes that Biden is too weak, that America is too divided, and that he will prevail in a game of chicken. He may be right, but Biden (who was very close to McCain) is ol’ school when it comes to Putin.
So, I fear that this could escalate rather quickly, which begs the question: Is Ukraine really worth the potential costs? On the other hand, rewarding Putin via concessions has long term costs, above and beyond empowering Putin. Can the United States be a trusted friend?
Lots of moving parts in war gaming the options. I do not know enough to weigh the green light/red light options. But, I am also very curious how the Average Joe Russian citizen feels about spilling blood to acquire Ukraine. And that really is Putin’s vulnerability and exposure, imho.