Para-military training? The FBI and BATF finally qualify!
Police the police? The FBI again, and the Internal Affairs division of every force gets lumped in.
Urban riot agitators? Have Rodney King and OJ Simpson been notified?
Lone individuals? So now the entire population at every Star Trek convention is suspect? Well, it's about time! =^)
Insurgents, rebels? Pee-Wee Herman? ("I'm a loner, Dottie, a rebel.")