We'd better hope that a third possibility is more likely... ... That this turns into something like one of the cold-war proxy wars. The West does not cross th

We'd better hope that a third possibility is more likely... ... That this turns into something like one of the cold-war proxy wars. The West does not cross the line by sending NATO troops or planes into Ukraine to fight Russian forces. The West does send in arms, but Russia limits its attempts to stop that to actions within the borders of Ukraine (not, for example, bombing Polish rail lines used to ship arms to Ukraine). The conflict in Ukraine goes on for more or less time as a hot war. An unlikely possibility is that Ukraine wins the hot war, humiliating Putin, and probably leading to his downfall (hopefully without any disastrous last gasp of aggression), or possibly the overflow of Putin comes first, with the new regime negotiating a way out that's at least somewhat tolerable for Ukraine. The more likely possibility is that Russia wins the hot war, imposes a puppet government, and the West opposes this outcome only by economic sanctions and covert arms shipments to insurgents (who will quite likely exist). This doesn't lead directly to escalation, though the stage might well be set for further crises. If further crises don't cause drastic change, Russia (current or future regime) may eventually tire of fighting an insurgency in Ukraine, and perhaps settles for absorbing the eastern part, while letting the western part become independent again (but probably "Finlandized"). A lot of people die. Once the immediate crisis is over it would be worth thinking about why people in power, on all sides, let it get to this point. I think it's unlikely that the situation was just that there were good guys, and bad guys, and all that one can say is that the bad guys were bad... Treating this as a simple morality play is likely to lead to a repeat performance.