The Department of the Navy is "the executive part of the Department of Navy at the seat of government; the headquarters, US Marine Corps; the entire operating forces of the US Navy and of the USMC, including the Reserve Component of such forces; all field activities, headquarters, forces, bases installations, activities, and functions under the control or supervision of the Secretary of the Navy; and the US Coast Guard when operating as a part of the Navy pursuant law."
Office of the Chairman of the Joint Chiefs of Staff. (2019). Dictionary of Military and Associated Terms. Washington DC: The Joint Staff.