The US also has a huge, cellular, distributed, militarized police force. Under Trump, that’s the real immediate threat. They’ve had decades of dehumanizing their fellow citizens and are eager to employ military tactics and authoritarian rule to a population they see as sheep. Many of them are part of unregulated militias as well.

A US civil war or revolution would almost certainly look like guerilla leftists and military deserters vs military hardliners and the police. On the upshot, a lot of police are actually soft babies and probably wouldn’t stick it out for protracted fighting.

Militias could dig in and hold a lot of territory under martial law in some areas though. Appalachia just a hive of little forts and compounds.