Updated March 5, 2020
Defense Primer: The Military Departments
Departments within a Department
military department’s general counsel, inspector general,
There are three military departments within the Department
and chief of legislative liaison.
of Defense (DOD): Department of the Army, Department
After first informing the Secretary of Defense, a Secretary
of the Navy, and Department of the Air Force. The
may make recommendations to Congress relating to DOD.
authority, function, and organization of each military
Other discretionary functions include the authority to
department is established in Title 10 of the United States
assign, detail, and prescribe the duties of civilians and
Code. Since 1947, the military departments have fallen
servicemembers. The Secretary also issues regulations that
under the Secretary of Defense’s authority, direction, and
implement his or her duties, powers, and functions. Under
control. According to the Goldwater-Nichols Act of 1986
the Uniform Code of Military Justice (UCMJ), the
(P.L. 99-433), the military departments are limited to
Secretary is the most senior final disposition official and
primary responsibility for personnel, training, services,
general court martial convening authority within the
supply, and procurement. Under this Act, the authority to
military department.
conduct military operations exclusively resides in the
unified combatant commands, which directly report to the
Armed Service
Secretary of Defense and the President.
There are one or more armed services in each military
Department
department under the authority, direction, and control of a
Secretary. The armed services are the Army, Marine Corps,
The authority to establish military departments
Navy, Air Force, and Space Force. Each armed service is
constitutionally resides with the Congress, not the
led by a service chief and supported by a service staff.
Commander in Chief. A military department provides and
embodies traditional civilian control of the military. A
military department consists of an executive headquarters
The Coast Guard is an armed service that operates in
and various agencies, installations, or field headquarters.
the Department of Homeland Security (DHS) under
Within the executive headquarters, the number of people
the leadership of the Commandant of the Coast
authorized to serve in the Office of the Secretary is
Guard and DHS Secretary, unless placed under the
specified in law and varies among the military departments.
authority, direction, and control of the Department of
Table 1 includes the total number of civilian personnel and
the Navy.
military officers authorized and the number of military
officers authorized within the total for each military
department. All civilians and servicemembers under the
Armed Service Chief
control or supervision of a service Secretary make up the
The President appoints a service chief from the flag or
personnel within a military department.
general officers of a service for four years with the advice
and consent of the Senate. The service chief is responsible
Table 1. Office of the Secretary Personnel Limitations
to the Secretary and Congress. Among other duties and
Number Authorized for Permanent Duty
responsibilities, the service chief exercises supervision over
the civilians, servicemembers, and organizations of the
ARMY
NAVY
AIR FORCE
armed service. The service chiefs are designated:
Total
Officer
Total
Officer
Total
Officer
Chief of Staff of the Army
3,105
1,865
2,866
1,720
2,639
1,585
Commandant of the Marine Corps
Source: 10 U.S.C. §§7014, 8014, 9014 (FEB, 2020)
Chief of Naval Operations
Note: Personnel limitations are not applied in time of war.
Chief of Staff of the Air Force
Secretary
Chief of Space Operations
Each military department is led by a Secretary whom the
These service chiefs serve as members of the Joint Chiefs
President appoints from civilian life with the advice and
of Staff (JCS) and are directly responsible to the Chairman
consent of the Senate. Each Secretary directly reports to the
of the Joint Chiefs of Staff (CJCS), Secretary of Defense,
Secretary of Defense, who directly reports to the President.
and President regarding operational matters. Unless it
Among other things, the Secretary is responsible for
conflicts with a service chief’s position on the JCS, the
organizing, equipping, and training the armed service or
service chief may disclose operational matters that affect
services in the military department.
the military department to the Secretary.
The Office of the Secretary typically includes an Under
Secretary and various Assistant Secretaries. Principal
officials who directly report to the Secretary include the
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Defense Primer: The Military Departments
Armed Service Staff
The Department of the Air Force
The service staff assists the service chief in carrying out his
The executive headquarters of the Department of the Air
or her responsibilities. Except as required by law, a
Force consists of the Office of the Secretary of the Air
Secretary determines a service staff’s members, duties, and
Force, Air Staff, and Office of the Chief of Space
titles. The principal role of a service staff is to furnish
Operations (see Figure 3). The Secretary’s general powers
professional assistance to the service chief and the
and duties are set forth in 10 U.S.C. §9013. The Department
Secretary, Under Secretary, and Assistant Secretaries of the
of the Air Force includes air, space, and cyberspace forces
military department.
of the Air Force and Space Force, which are the principal
air and space armed forces. The Air Force consists of the
The Military Departments
Regular Air Force, Air Force Reserve, and Air National
Under the leadership of its Secretary, each military
Guard of the United States. The United States Space Force
department provides conventional, strategic, and special
consists of the Regular Space Force.
operations forces to conduct operations as defined by the
President and Secretary of Defense. Each military
Figure 3. Department of the Air Force
department supports other military departments and the
Secretary of the Air Force
joint forces.
Office of the Secretary of the Air Force
The Department of the Army
Chief of Staff of the Air
Chief of Space
The executive headquarters of the Department of the Army
Force
Operations
consists of the Office of the Secretary of the Army and the
Army Staff (see Figure 1). The Secretary’s general powers
The Air Staff
The Space Staff
and duties are set forth in 10 U.S.C. §7013. The Department
The Air Force
The Space Force
of the Army includes land, aviation, and cyberspace forces
Source: CRS
of the Army, which is the principal land armed force. The
Note: P.L. 116-92 established the Space Force on December 20,
Army or Armies referred to in the Constitution of the
2019 by creating the Chief of Space Operations position and
United States consist of the Regular Army, Army Reserve,
redesignating the Air Force Space Command as the U.S. Space Force.
and Army National Guard of the United States.
Figure 1. Department of the Army
Relevant Statutes
Secretary of the Army
10 U.S.C. §§ 111, 7011, 8011, 9011
Office of the Secretary of the Army
10 U.S.C. §§ 113, 7013, 8013, 9013
Chief of Staff of the Army
10 U.S.C. §§ 7014, 8014, 9014
Army Staff
10 U.S.C. §§ 7031, 8031, 8041, 9031, 9081
The Army
10 U.S.C. §§ 7032, 8032, 8042, 9032
Source: CRS
10 U.S.C. §§ 7033, 8033, 8043, 9033, 9082
The Department of the Navy
The executive headquarters of the Department of the Navy
consists of the Office of the Secretary of the Navy, Office
CRS Products
of the Chief of Naval Operations, and Headquarters Marine
Corps (see Figure 2). The Secretary’s general powers and
CRS In Focus IF10543, Defense Primer: The Department of
duties are set forth in 10 U.S.C. §8013. The Department of
Defense, by Kathleen J. McInnis
the Navy includes naval, land, air, and cyberspace forces of
CRS In Focus IF10544, Defense Primer: Department of the Army
the Navy and Marine Corps, which are the principal
and Army Command Structure, by Barbara Salazar Torreon and
maritime armed forces. The Navy consists of the Regular
Andrew Feickert
Navy, Fleet Reserve, and Navy Reserve. The Marine Corps
CRS In Focus IF10484, Defense Primer: Department of the Navy,
consists of the Regular Marine Corps, Fleet Marine Corps
by Ronald O'Rourke
Reserve, and Marine Corps Reserve.
CRS In Focus IF10547, Defense Primer: The United States Air
Figure 2. Department of the Navy
Force, by Jeremiah Gertler
CRS In Focus IF10542, Defense Primer: Commanding U.S.
Secretary of the Navy
Military Operations, by Kathleen J. McInnis
Office of the Secretary of the Navy
This InFocus was previously published by Heidi Peters,
Chief of Naval
Commandant of the
Analyst in Defense Acquisition.
Operations
Marine Corps
Alan Ott, Analyst in Defense and Intelligence Personnel
The Navy Staff
The Marine Staff
The Navy
The Marine Corps
Policy
Source: CRS
IF10550
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Defense Primer: The Military Departments
Disclaimer
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