While an organized military force could easily occupy large swaths of America if they were inclined to do so, a bunch of alphabet agencies with no real coordination, armed only with handguns, would get their @$$es handed to them, in short order. Think Waco, only without Koresh's decision to let up when the BATF ran out of ammo.
There's something else going on here. Why the DHS won't fess up is what's puzzling and troubling.
DHS I believe wants to eliminate the FBI and any other three letter agency so it can be the New Gestapo, Hitler had the same problem with the gestapo warring with other police units.
Maybe they think they’ll have the People’s Liberation Army backing them.