The United States Department of Defense (DoD) is the federal department in charge of coordinating and supervising all agencies directly involved with national security and military affairs. The DoD is one of the largest tenants at The Pentagon and consists of three chief sub-departments, the Department of the Army, the Department of the Navy and the Department of the Air Force.
Alternative DOD groups include the National Geospatial-Intelligence Agency (NGA), the Missile Defense Agency, the Defense Advanced Research Projects Agency (DARPA), the Pentagon Force Protection Agency (PFPA), the Defense Intelligence Agency (DIA) and the infamous National Security Agency (NSA).
In terms of the department’s history, it was set up based on some specific ideas drawn up by the Joint Chiefs of Staff and on 19 December 1945, President Harry S. Truman proposed the creation of a unified Department of National Defense. The proposal was debated over and was not made law until 1947.
On July 26, 1947, President Truman finalized the National Security Act of 1947 which set up the National Military Establishment which would begin active operations in September, 1947. The Establishment had the ill-fated abbreviation NME which sounds very much like ‘enemy’ and it was, in 1949, renamed the DoD.
Prior to the creation of the DoD, US armed forces were separated into different departments which diluted any real central authority. The Marine Corps remained as a separate service under the control of Naval Department while the Coast Guard remained under the control of the Treasury Department.
The Department’s budget was about $787 billion in 2007 though this figure does not include tens of billions more in spent on ‘supplementary’ things like nuclear weapons tests.
The Department has authority over the Coast Guard in wartime. The Coast Guard is always considered one of the five branches of the US armed services, according to the US Code. During times of declared war the Coast Guard works as a section of the Navy even though the Coast Guard has not been under the full control of Navy since World War 2.
The official command structure of the Department of Defense is set down by the Goldwater-Nichols Act of 1986, made law by President Ronald Reagan in October, 1986. This Act altered the command of the United States military and it introduced the most significant changes to the Department since it was established.
Under the Act, the chain of command passes from the US President, through the Secretary of Defense, to the commanders of all military forces (COCOM). The Chairman of the Joint Chiefs is mainly responsible for readiness of the US military and behaves as the President’s military adviser while remaining firmly outside of the chain of command.
