I don’t think or believe Putin will necessarily win the war by escalating to the use of nuclear weapons.

I just think he has been very consistent in “doing what he says, and saying what he does” over the long-term.

And that his personal credibility is tied to this conflict, so escalation is likely.

Escalation by Putin doesn’t guarantee victory(or the semblance of it), but de-escalation by Putin is a guarantee of failure(credibility).

The US has just leaked its unhappiness with Ukraine conducting targeted assassination in Russian territory(seperate from train/logistics sabotage).

But a dirty bomb detonated in Russian territory is far more likely to be a Russian casus belli, akin to Nazi false flag action in Poland in 1939 and Putin/Shoigu false flag action in 1999 with the Moscow Apartment Bombings.