This is a poor analog. The USA constantly and wholly backs the land-grabs of Israel, a nuclear power. You could argue that pummeling the ethnic Palestinians “stabilizes” the region, and then I’d say the same about Russia “pummeling” the Ukrainians. Rather, the reality just boils down to “Israel good, Russia bad.”
The US government and media monolith is traditionally dead silent about border clashes between India and Pakistan, two other nuclear powers. While that conflict has not yet escalated into serious casualties or looming war, by your metric, it would also warrant some massive international intervention. Yet, the Global American Empire holds no position (it would wait for China’s reaction before telling us how to think).