Walter Russell Mead runs through the various options in Ukraine, and his analysis of what it would take to truly defeat Putin isn’t very encouraging:
The first option, helping Ukraine win, is the most emotionally appealing and would certainly be the most morally justifiable and politically beneficial, but the risks and costs are high. Russia won’t accept defeat before trying every tactic, however brutal, and perhaps every weapon, however murderous. To force Russia to accept failure in Ukraine, the Biden administration would likely have to shift to a wartime mentality, perhaps including the kind of nuclear brinkmanship not seen since the Cuban missile crisis of 1962. With China and Iran both committed to weakening American power by any available means, a confrontation with the revisionist powers spearheaded by Russia may prove to be the most arduous challenge faced by an American administration since the height of the Cold War.