Perhaps the BEST B1G Forum anywhere, here at College Football Fan Site, CFB51!!!

NATO has had a vested strategic interest in border stability in Europe, it's really one of their unwritten rules.  When a country starts moving a border using military force, it's pretty serious.  It can happen in Africa and they don't get too worried, or Yugoslavia can break up and it's "OK" except for the strife that followed.  The core idea is that borders are sacrosanct.  Nobody should be allowed to change any of them by force.  Crimea worried everyone but there didn't seem to be any option.  I think folks figured "OK, it used to be Russia, we'll use harsh naguage and let it go."  The idea Russia could basically run over Ukraine and install their own rump government was viewed differrently.  When Ukraine resisted, it obviously encouraged support to keep them humming.

This is inherent in Article V, which of course doesn't include Ukraine fortunately.

I think the other interest is to bleed Russia dry and get rid of Putin.  "We" are putting in "money" basically and Russia is putting in troops.  Ukraine is our mercenary force.

I don't think we'd launch a first strike on Russia and if we did, there is little chance we'd knock out everything, and even ten remaining for counterstrike would be ...

WTF...

Live updates: Latest news on Russia and the war in Ukraine (cnbc.com)

An international team of investigators said in a new report that it is “highly likely Russian forces deliberately destroyed” the Kakhovka dam in southern Ukraine.

“We find there is a high probability the collapse of the dam was caused by pre-emplaced explosives positioned at critical points within its structure,” explained Catriona Murdoch, a lawyer and expert in starvation-related crimes, who was also part of one of the first delegations to arrive at the site.

One reason I tend to believe this is how tough it would be to take out a dam externally with some weapon.

An Anglo-American operation did it to some German dams 80 years ago and it took a LOT of planning, design, and effort:   

https://youtu.be/aHGgXi4Kwqw

Russia-Ukraine aside, I don't think big, obvious county-vs-country war is a thing anymore, when it comes to the top handful of countries.
.
That's why I find it more likely 1 nuke is slipped in and set off, with mystery/debate/uncertainty over who done it is more likely than what a conventional strike would look like.  Another way that I find more likely is one country hacking another's weapons systems and getting them to nuke themselves.
.
Both scenarios, however unlikely, are absolutely less % chance of "mutually assured destruction."  Both have deniability built in. 

If he had been thinking logically at any point during the last two years, he wouldn't have invaded Ukraine, and Russia wouldn't find themselves in the jam they're in.