[chmod600]

Yeah, I mean even Putin doesn't know the real odds.

It probably depends a lot on the exact circumstances/timing. And in the war, circumstances change all the time.

Putin wants us to believe it's a Dr. Strangelove situation, where no humans make a choice and therefore nuclear annihalation is a guarantee if we cross a line. But that's false.

Any line Putin draws can be tested and shifted along various axes: who crosses it, how bad it is for Russia, how egregious the violation is, how well it can be argued that it's not a violation, how long it takes to confirm that a violation has taken place, how certain he is that a violation has taken place, who authorized it, how long it takes to confirm who authorized it, etc.

And we don't know for sure that Putin can unilaterally initiate a world-ending strike without anyone in the chain second-guessing him.