Mass shootings by lone gunmen or coordinated mass shootings by multiple gunmen, especially on “liberal” targets
Roaming militias causing violence skirmishing with police/natl guard
Checkpoints/Roadblocks
States seceding (sounds dramatic but there’s def some governors crazy enough)
Widespread rioting
Really a million scenarios. All of which just take a little coordination. They have the means, the anger, and the will to do these things. If enough people take part, it’ll be a war. Not a conventional one, but think guerilla style counter insurgent type of war.