My sweet summer child. You know how LRADs are deployed against US civilians? You know how chemical munitions are deployed against US civilians? (Specifically munitions that are considered illegal to deploy in war, but are apparently acceptable to deploy by police?) How flashbang grenades launched from handheld launchers are deployed against US civilians? How about the military personnel carriers and MRAPs?

You think those didn't start as restricted to some theater of war?

Go read up on the 1033 program. Or the DHS Grant Program, the Justice Assistance Grant program, or the 1122 program.