There has been an attempt at a balancing act by USA and Europe, and while Europe has abandoned the idea, USA is keeping it.
The idea is that if Russia lose to much to quickly, it may destabilize Russia, and that could create a dangerous situation with the Russian nukes.
So USA was sort of in a Limbo, that Russia could not be allowed to win, but they couldn’t be allowed to lose and be destabilized either.
This idea however is becoming less and less popular in USA, and there is speculation that USA will soon lift these restrictions.