They would be tried in the military courts for treason or sedition.
I initially thought that but not clear they can make the case that their action were in aid of a foreign government/enemy’s attack on US interests. I believe that would be required to reach the level of treason. Don’t misunderstand me. Even if their were not a foreign government involved, I see their actions as a demostic terrorist organizations seeking to establish a government to replace ours. Aka coup d’état (rebellion).