If it were a first strike, it would have to be brutal. Like old west gunfighters, you better kill that guy with your first bullet or he will kill you with his. If Vlad felt the need to nuke someone, he would have to nuke everyone, hard, because once he launches, he absolutely knows he will get hit back harder, or at least as hard as the other guys are capable of. And with Tridents browsing about out there, he cannot knock the other guys completely.
Hence, MAD play is kind of a fool’s gambit. And like field war, nuclear war does not determine who was right, only who (what) is left.
It might be possible to get away with a first-strike on environmental grounds.
Russia could nuke New York City, then tell America, “We’ve already brought the planet this close to ecological ruin. If you hit back, that’s your right, but consider this: then more and more soot and ash will be kicked up into the atmosphere as we keep nuking back and forth, and 8 billion of us will inhabit an even-worse, past-the-point-of-no-return atmosphere-wrecked planet.”
I would not rule out the chance to preserve a nucleus of human specimens. It would be quite easy at the bottom some of our deeper mine shafts. Radioactivity would never penetrate a mine some thousands of feet deep, and in a matter of weeks, sufficient improvements in dwelling space could easily be provided.
Nuclear reactors could provide power almost indefinitely. Greenhouses could maintain plantlife. Animals could be bred and slaughtered. A quick survey would have to be made of all the available mine sites in the country. But I would guess… that ah, dwelling space for several hundred thousands of our people could easily be provided.
What if Putin thinks we ARE bluffing? If he drops a tactical nuke on Kiev, are you sure Biden and NATO will commit to global thermonuclear devastation? Or will they decide Ukraine isn’t worth suicide?
I grew up on the tail end of the Cold War, so I understand the concept of mutually assured destruction. But why would NATO nations reciprocate if Ukraine was the target of a nuclear attack? Ukraine is isn’t part of NATO. An attack on Ukraine is not an attack on the United States, France, or Great Britain.
Then World War III is over and Russia has won, because the west has in effect surrendered by showing that Russia can use nuclear force to achieve its aims with impunity.
There is no reason the West has to make ANY nuclear decision in minutes. That’s the whole purpose of ballistic-missile submarines - they buy you lots of time. Land-based ICBMs and bombers can be destroyed within an hour by an enemy, but your submarines will survive and you can still call upon them to retaliate long after the first attack.
Which means making it absolutely clear that any nuclear strike on Russia’s part will be met with immediate and massive reprisal in kind. It’s the only effective deterrent in our arsenal.