If Peter Zeihan is to be believed (the first bullet is his point, he has explicitly said what follows is what he's heard from some folks), here's the calculus at the strategic level:
-Russia will not stop with Ukraine, they will continue expanding till they have secured defensible borders. They view it as an existential problem.
-The Russian military has proven to be awful and would get monkey stomped by the western/NATO coalition that would meet them. Which means there is almost no way to avoid a nuclear exchange.
-So the Russian military needs to be attritted in Ukraine. Win, lose, or draw, what remains needs to be incapable of continued offense.
If that is actually what is going on in the head-shed. I'd imagine this is a blank check.