10 U.S.C. § 10203

(a) The Secretary of the Army may designate a general officer of the Army to be directly responsible for reserve affairs to the Chief of Staff of the Army. (b) The Secretary of the Navy may designate a flag officer of the Navy to be directly responsible for reserve affairs to the Chief of Naval Operations and a general officer of the Marine Corps to be directly responsible for reserve affairs to the Commandant of the Marine Corps. (c) The Secretary of the Air Force may designate a general officer of the Air Force to be directly responsible for reserve affairs to the Chief of Staff of the Air Force. (d) The Secretary of Homeland Security may designate a flag officer of the Coast Guard to be directly responsible for reserve affairs to the Commandant of the Coast Guard. (e) This section does not affect the functions of the Chief of the National Guard Bureau, the Chief of Army Reserve, or the Chief of Air Force Reserve.