> Clearly if these people torching the cars are waving foreign flags, they are a foreign enemy and thus the military is appropriate, no?

No. Torching cars is already a crime and the city and state were already restoring order. The kind of flag waved while a car is torched does not change the calculus. Critically, a US citizen does not cease to be a US citizen because they waved a foreign flag; we have free speech in the United States, and flag-waving is protected by the first amendment.

Also worth noting that none of this would have happened if the regime didn't deliberately provoke it in the first place.