Currently, the army is divided into the Regular Army, the Army Reserve, and the Army National Guard. The army is also divided into major branches such as Air Defense Artillery, Infantry, Aviation, Signal Corps, Corps of Engineers, and Armor. Before 1903 members of the National Guard were considered state soldiers unless federalized (i.e., activated) by the President. Since the Militia Act of 1903 all National Guard soldiers have held dual status: as National Guardsmen under the authority of the governor of their state or territory and, when activated, as a reserve of the U.S. Army under the authority of the President.
The Air Defense Artillery is a branch of what?
the Army