This is what really scares me. Are you up for a game of Russian Roulette with nuclear weapons? How do you know what is in Putin's mind? We can all speculate, but do we want to risk a nuclear apocalypse on the basis of a bad guess? Too many Americans are now thinking along these lines. It's utter madness.
I admit that I've seen similar reasoning coming out of Russia--that they can have a limited incursion into NATO countries under certain circumstances and that NATO would not dare risk nuclear retaliation, especially with Russia having those hypersonic missiles that could take out the US before we knew they were coming. IIRC, that one came from some deputy minister of defense. There are clearly people there who think they can get away with the same kind of dangerous calculation.
Let's imagine that NATO troops start advancing into Ukraine to try to rescue them from the atrocities they are suffering. What would you think, if you were sitting in the Kremlin and saw that? How far towards Russia would those troops be moving? Would they stop at Ukraine's border? That would be sufficient to trigger a nuclear retaliation. Do you think it would be a limited strike just to send a message? I don't.
The US and Russia are not the only nuclear-armed powers in the world. China has ICBMs, too. Russia has nuclear-armed submarines, in case their a ability to strike from land is wiped out. And both sides have
MIRVs. A nuclear exchange is not going to be survivable. I'd rather not trust in speculation over how sane Putin is, especially when the risk being proposed assumes he is more sane than we are.