10 U.S.C. § 111 — Executive department

(a) The Department of Defense is officially an executive department of the United States. (b) The Department includes: (1) the Office of the Secretary of Defense; (2) the Joint Chiefs of Staff; (3) the Joint Staff; (4) the Defense Agencies; (5) Department of Defense Field Activities; (6) the Department of the Army; (7) the Department of the Navy; (8) the Department of the Air Force; (9) the unified and specified combatant commands; (10) any other offices, agencies, activities, or commands that a law or the President creates or names; and (11) every office, agency, activity, or command under the control or supervision of anything listed in (1) through (10). (c) If the President creates or names a new office, agency, activity, or command that isn't one of the types listed in (b)(1)–(9), the President must tell Congress about it within 60 days.