What's the first thing people think of when someone says "nukes"? Hiroshima, Nagasaki, doomsday, end of the World, etc.

So I'll throw this out there because I was in when it became a "big thing/great idea" in the early 80s: tactical/battlefield nukes. Limited nukes that can be fired from tanks/artillery. Still going to make the place glow, just a much smaller place. Both the Russians and US came up with that great idea, then most of Europe wouldn't let us deploy them. Didn't stop Brezhnev.

The US has unmatched air superiority. On the ground, the Russians have us at least 4-1 in tanks and artillery and an even bigger disadvantage manpower-wise. Note that this does not account for NATO manpower and materiel.

Anyhoo, I suspect (yep, a guess) this is what Putin is threatening to use. Ukraine/Europe's no good to anyone if it's uninhabitable for a thousand years. Russia is way ahead of everyone in nukes. Good thing SALT I and II applied to BOTH parties IIRC, the tactical nukes are not included in SALT I or II, but we didn't pursue them while Russia did.

No matter what, everyone loses.