I think the "secret police" part is a red herring. My opinion is that the federal police were justified defending the courthouse, but were not justified hunting around for suspects in vans, unmarked or not(this is the state police's job!), but I don't think too many would agree that the federal vs state divide is what's important, which is why I didn't bring it up initially. I feel the anger against the federal agents is not rooted in principle, but the principles are used as a rationalization for removing an opposing force to the protests.

Hopefully we can agree that it's well within police prerogative to prevent rioting, serious property damage(like trying set fire to buildings), possible violence. I am definitely willing to concede that Trump is a tactless brute, and sending the federal agents in like this was far from the best strategy. We could even perhaps tentatively agree that his actual goal is to disperse the protests under the guise of preventing rioting, but again, we'd have to agree first that the rioting is there.

Which brings me back to the original post - is there protesting or violent rioting? Both. Is there secret police or not? Not really - there should be police to monitor the protests and prevent the rioting. If the state police is unwilling to do it, then the federal police may have to step in, although I'd have preferred to exhaust B through Y instead of going straight from A-Z.