Good luck with hypersonic nukes when your patrols are pecked by ambushes and FPV drones in the spaghetti of neighborhoods with opposing alignments.

Except this violence will absolutely be preceded extensive operations by the giant existing police and national guard presence that knows the neighborhoods like the backs of their hand. They would put a giant dent in that well before a single shot was fired. Would that absolutely be the case if we invaded, say, Canada? Quite likely. The US government has so much existing control on US soil that I'd eat my hat if any US city lasted a week in active conflict.