That's funny, because now that the feds are gone it's peaceful again.
https://www.theguardian.com/us-news/2020/jul/31/portland-protests-latest-peaceful-night-federal-troops-withdrawal
Not surprising at all. Setting aside the "professionals" who on other days would be football hooligans, we are talking about highly frustrated (to say it friendly) people here.
The situation has already exploded. People are on the streets and they are angry. Boy, are they angry!
You now have 2 (well, really 3) options:
1. Do the "firefighter" approach: Try to outwait it and let it burn down. (Not made easier with more bad things coming from cops and the orange ape with his fans.)
If something is already burning and you can't safe it securely, let it burn down and protect the houses around. And in this case it might even be literally the courthouse. After that the people have hopefully vented enough anger.
2. Trample out the fire. Use massive police forced (a... delicate move since the protests are about police violence), clouds of tear gas etc. You might succeed in getting people from the streets. But all you have done is gotten rid of the smoke. The fire is still burning underground, and who knows where it might spread and when it pops up again? And when it does, it will be at least as bad as before.
3. The dictatorial approach. Send in the army. Shed blood. Tiananmen-style. Scare the people more by your reaction than they are scared of the current situation. You make mortal enemies for life, but you may succeed in quelching the fire. Like taking out all oxygen out of a burning space craft. The fire is out, but anyone not in a functioning space suit... (aka run away in time)
The very worst thing you can do is pull off a 2.5
Like kidnapping a few people with unmarked vehicles and unidentified forces (or some that have no right to be there).
You don't scare people enough to hush up, but you give them more fear about the current situation. Or more reason to do whatever comes into their mind. Fear driven people WILL riot violently. (Which does not necessarily mean they damage a lot. They attack the oppressor, and who or what that is can be very different.)
An actual example of this is Hongkong. China has made the screws tighter an tighter. And with not allowing the protesters as candidates, they are basically at a 2.3 now.
If the Honkong people don't accept the result of the upcoming election, then either China has to do a strategic withdrawel (back to the 50-year contract) or there will be a real civil war and China will send in the tanks. With Corona and the orange ape on the other side, my bets are on the tanks.