Yes. The Federal Occupation force can and should arrest anyone committing crimes on Federal Land.

Whether or not it was even necessary to deploy them to a City where the protests had largely dissipated, I guess depends on whether or not you have an election to win with a base that enjoy's watching Americans fired upon like the enemy.

Trump will take this as far as you guys allow him to. Nothing is off the table in that regard. Now that you believe your fellow citizens are the enemy, there's no reason to believe we the people wont be dealt with in the same manner as the rest of the list of enemies on your list.

Which at this point seems to be the rest of the entire world, except Russia and North Korea.