Judging from the amount of prestige and resources Russia has poured into it, Putin seems committed to risk at least limited military action in the Ukraine. It could be a repeat of Putin’s earlier campaign of subversion or involve a conventional overt component.
America’s dilemma is to respond without escalating the military conflict while potentially turning Ukraine, to mix metaphors, into Putin’s Vietnam.
The danger of escalation was underscored by Turkey
Turkish President Recep Tayyip Erdogan warns Russia against invading Ukraine, calling the former Soviet republic a “powerful” country with international friends.
“You cannot handle these things by saying ‘I will invade something, I will take it,’” Turkish media quotes Erdogan as saying. “I don’t see Russia’s invasion of Ukraine as a realistic approach because it is not an ordinary country. Ukraine is a powerful country.”
https://www.timesofisrael.com/liveblog_entry/erdogan-urges-russia-not-to-invade-ukraine/