Organizational structure of the United States Department of Defense

The United States Department of Defense (DoD) has a complex organizational structure. It includes the Army, Marine Corps, Navy, Air Force, and the Unified combatant commands, U.S. elements of multinational commands (such as NATO and NORAD), as well as non-combat agencies such as the Defense Intelligence Agency and the National Security Agency. The DoD's annual budget was roughly US$496.1 billion in 2015. This figure is the base amount and does not include the $64.3 billion spent on "War/Non-War Supplementals". Including those items brings the total to $560.4 billion for 2015.

Civilian control over matters other than operations is exercised through the three service departments, the Department of the Army, the Department of the Navy (which includes the Marine Corps), and the Department of the Air Force. Each is led by a service secretary, who is below Cabinet rank.

In wartime, the Department has authority over the Coast Guard, which is under the control of the Department of Homeland Security (DHS) in peacetime. Prior to the creation of DHS, the Coast Guard was under the control of the Department of Transportation, and earlier under the Department of the Treasury. According to the U.S. Code, the Coast Guard is at all times considered one of the five armed services of the United States. During times of declared war (or by Congressional direction), the Coast Guard operates as a part of the Navy; this has not happened since World War II, but members have served in undeclared wars and conflicts since then while the service remained in its peacetime department.

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