the NATO/EU/US may decide to become directly involved in the war
After their involvement, I doubt they’d do nothing if some of their soldiers get shredded by a Russian bomb. Let’s imagine Russia is beaten and it’s on the brink of complet defeat. Do you really not expect them to send nuclear warheads everywhere before collapsing as an ultimate fuck you ? 10% of the warheads are enough to turn earth into a post apocalyptic wasteland.