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Updated December 22, 2020
Defense Primer: The Military Departments
Departments within a Department
Department of the Navy
There are three military departments within the Department
The executive headquarters of the Department of the Navy
of Defense (DOD): Department of the Army, Department
consists of the Office of the Secretary of the Navy, Office
of the Navy, and Department of the Air Force. A military
of the Chief of Naval Operations, and Headquarters Marine
department provides and embodies traditional civilian
Corps (see Figure 1). The Secretary’s general powers and
control of the military. The authority, function, and
duties are set forth in 10 U.S.C. §8013. The Department of
organization of each military department are established in
the Navy includes naval, land, air, and cyberspace forces of
Title 10 of the United States Code. Since 1947, the military
the Navy and Marine Corps, which are the principal
departments have fallen under the Secretary of Defense’s
maritime armed forces. The Navy consists of the Regular
authority, direction, and control. According to the
Navy, Fleet Reserve, and Navy Reserve. The Marine Corps
Goldwater-Nichols Act of 1986 (P.L. 99-433), combatant
consists of the Regular Marine Corps, Fleet Marine Corps
commands are responsible for military operations, whereas
Reserve, and Marine Corps Reserve.
military departments are responsible for personnel, training,
services, supply, and procurement.
Department of the Air Force
The executive headquarters of the Department of the Air
Military Departments
Force consists of the Office of the Secretary of the Air
Under the leadership of its Secretary, each military
Force, Air Staff, and Office of the Chief of Space
department provides conventional, strategic, and special
Operations (see Figure 1). The Secretary’s general powers
operations forces to conduct military operations within a
and duties are set forth in 10 U.S.C. §9013. The Department
combatant command. A military department consists of an
of the Air Force includes air, space, and cyberspace forces
executive headquarters and various agencies, installations,
of the Air Force and Space Force, which are the principal
or field headquarters.
air and space armed forces. The Air Force consists of the
Regular Air Force, Air Force Reserve, and Air National
Within the executive headquarters, the number of people
Guard of the United States. The United States Space Force
authorized to serve in the Office of the Secretary is
consists of the Regular Space Force.
specified in law and varies among the military departments.
Table 1 includes the total number of military officers and
Figure 1. Military Department Structure
civilian personnel authorized for each military department,
and the number of military officers authorized within the
Secretary of the Army
total. All civilians and servicemembers under the control or
Office of the Secretary of the Army
supervision of a service Secretary make up the personnel
Chief of Staff of the Army
within a military department.
Army Staff
Table 1. Office of the Secretary Personnel Limitations
The Army
Number Authorized for Permanent Duty
Secretary of the Navy
ARMY
NAVY
AIR FORCE
Office of the Secretary of the Navy
Total
Officer
Total
Officer
Total
Officer
Chief of Naval
Commandant of the
3,250
1,900
3,150
1,800
2,750
1,650
Operations
Marine Corps
Source: 10 U.S.C. §§7014, 8014, 9014 (December 2020).
The Navy Staff
The Marine Staff
Note: Personnel limitations are not applied in time of war.
The Navy
The Marine Corps
Department of the Army
Secretary of the Air Force
The executive headquarters of the Department of the Army
Office of the Secretary of the Air Force
consists of the Office of the Secretary of the Army and the
Army Staff (see Figure 1). The Secretary’s general powers
Chief of Staff of the Air
Chief of Space
and duties are set forth in 10 U.S.C. §7013. The Department
Force
Operations
of the Army includes land, aviation, and cyberspace forces
of the Army, which is the principal land armed force. The
The Air Staff
The Space Staff
Army or Armies referred to in the Constitution of the
The Air Force
The Space Force
United States consist of the Regular Army, Army Reserve,
Source: CRS analysis based in Title 10 U.S. Code
and Army National Guard of the United States.
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Military Department Secretaries
Under Secretary, and assistant secretaries of the military
Each military department is led by a Secretary whom the
department.
President appoints from civilian life with the advice and
consent of the Senate. Each Secretary directly reports to the
Secretary of Defense, who directly reports to the President.
The only armed force that is not in a military
Among other things, each Secretary is responsible for
department is the Coast Guard. It operates in the
organizing, equipping, and training the armed service or
Department of Homeland Security (DHS) under the
services in the military department.
leadership of the Commandant of the Coast Guard
and the authority, direction, and control of the DHS
The Office of the Secretary typically includes an Under
Secretary. However, Congress and the President may
Secretary of the military department, and various assistant
transfer the Coast Guard to the Navy (14 U.S.C.
secretaries with designated areas of responsibility.
§103).
Specified officials who directly report to the Secretary
include the military department’s general counsel, inspector
After the six armed forces, the remaining two
general, and chief of legislative liaison.
uniformed services are the commissioned corps of the
Public Health Service (PHS Corps), which is part of
After first informing the Secretary of Defense, a Secretary
the Department of Health and Human Services, and
may make recommendations to Congress relating to DOD.
the commissioned corps of the National Oceanic and
Other discretionary functions include the authority to
Atmospheric Administration (NOAA Corps), which is
assign, detail, and prescribe the duties of civilians and
part of the Department of Commerce.
servicemembers. The Secretary also issues regulations that
implement his or her duties, powers, and functions. Under
The PHS Corps and NOAA Corps have a contingent
the Uniform Code of Military Justice (UCMJ), the
role in the armed forces during wartime or if directed
Secretary is the most senior final disposition official and
by the President. While serving in this role, the PHS
general court martial convening authority within the
Corps would become a military service in DOD and a
military department.
branch of the land and naval forces (42 U.S.C. §217),
Military Department Armed Forces
and the NOAA Corps would transfer to any military
There are one or more armed forces in each military
department as considered to be in the best interest of
department. Each armed force is under the authority,
national security (33 U.S.C. §3061).
direction, and control of the military department’s
Secretary. An armed force is led by a service chief and
supported by a service staff. There are six U.S. armed
forces, five of which are in the military departments: the
Relevant Statutes
Army, Navy, Marine Corps, Air Force, and Space Force.
The six armed forces also comprise six of the eight U.S.
10 U.S.C. §§ 111, 7011, 8011, 9011
uniformed services.
10 U.S.C. §§ 113, 7013, 8013, 9013
Armed Forces Chiefs
10 U.S.C. §§ 7014, 8014, 9014
The President appoints a service chief from the flag or
10 U.S.C. §§ 7031, 8031, 8041, 9031, 9081
general officers of a service for four years with the advice
10 U.S.C. §§ 7032, 8032, 8042, 9032
and consent of the Senate. The service chief is responsible
10 U.S.C. §§ 7033, 8033, 8043, 9033, 9082
to the Secretary and Congress. Among other duties and
responsibilities, the service chief exercises supervision over
the civilians, servicemembers, and organizations of the
armed force. There are five service chiefs among the three
CRS Products
military departments (see Figure 1).
CRS In Focus IF10543, Defense Primer: The Department of
The service chiefs serve as members of the Joint Chiefs of
Defense, by Kathleen J. McInnis
Staff (JCS), which is led by a presidentially appointed and
CRS In Focus IF10544, Defense Primer: Department of the Army
Senate confirmed flag or general officer who serves as the
and Army Command Structure, by Barbara Salazar Torreon and
Chairman of the Joint Chiefs of Staff (CJCS), and is
Andrew Feickert
responsible to the Secretary of Defense and President
CRS In Focus IF10484, Defense Primer: Department of the Navy,
regarding military operations. Unless disclosure conflicts
with the service chief’s position on the JCS, a service chief
by Ronald O'Rourke
may disclose operational matters that affect the chief’s
CRS In Focus IF10547, Defense Primer: The United States Air
military department to its Secretary.
Force, by Jeremiah Gertler
CRS In Focus IF10542, Defense Primer: Commanding U.S.
Armed Forces Staffs
Military Operations, by Kathleen J. McInnis
The service staff assists the service chief in carrying out his
or her responsibilities. Except as required by law, a
Secretary determines a service staff’s members, duties, and
titles. The principal role of a service staff is to furnish
Alan Ott, Analyst in Defense and Intelligence Personnel
professional assistance to the service chief, Secretary,
Policy
IF10550
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Defense Primer: The Military Departments
Disclaimer
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