There seems to be a preponderance of reports that foreshadow the U.S. military detaining large numbers of activists or other troublesome people, when some sort of economic and/or societal collapse occurs. Am I going the way of the conspiracy nut, or are these valid?
The most striking is definitely Field Manual 3-39.40 by the U.S. Army (3.6 MB PDF file). This field manual offer 326 pages of advice on how to handle internment and detention, including if not mainly on U.S. soil.
In this story, many connections and plans are outlined.
I’ve also seen, and heard from friends, about bold urban training maneuvers done by U.S. military inside of the City of Boston, with the city government’s permission. This included landing helicopters on the roof of a nearby primary school, kicking dust into the eyes of tennis playing civilians who were shocked and scared to see military helicopters landing in their quiet Jamaica Plain neighborhood.