32 U.S.C. § 501: Training generally

(a) The discipline, including training, of the Army National Guard shall conform to that of the Army. The discipline, including training, of the Air National Guard shall conform to that of the Air Force. (b) The training of the National Guard shall be conducted by the several States, the Commonwealth of Puerto Rico, the District of Columbia, Guam, and the Virgin Islands in conformity with this title.