logically, putin should escalate first. there's a lot of things the russians have refused to do, like bomb out bridges, because the idea is to deflect the war to ukraine (the borderland) rather than fight it head-on in russia. putin isn't trying to conquer ukraine, he's just trying to keep the fighting out of russia, proper.
it's an old roman barbarian management tactic: the barbarians are going to fight you and there's not much you can do to stop it, so you keep the barbarians fighting away from the cities, instead of near them.
if ukraine is ordering 100 billion dollars of weapons, russia needs to treat this more like an actual war and try not a distraction mechanism, and try to win rather than just burn them out.