These things take on a momentum all of their own, declaring parts of Ukraine as sovereign Russian territory, as hes planning to do, will leave him with no choice but to escalate.
Do you seriously think a man like Putin & his cronies could face the humiliation, at home or abroad, of backing down to the West? He and Russia's role in the World is over at that point.
He is rapidly approaching the point where whichever way he turns, he has nothing left to lose, Which is exactly when rational thinking no longer plays a part.