Actually you are quite on the money here. The battlefields in Iraq, Afghanistan, Pakistan and elsewhere are used to test new weapons and technologies like armory, drones, sigint/mass interception devices, etc.
And then the equipment is brought back home and used against civilian targets. So now you have tanks even in small cities, drones patrolling the skies (flying over your head right now), face recognition cameras spreading, IMSI catchers etc and the whole country is becoming a 'militarized' society. All these systems have been test-run somewhere before. You also need a convenient playground for some more toxic types of weapons (think depleted uranium or stuff like that).