The United States Department of Defense (DoD) is the federal department which deals with 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 has three chief sub-departments, the Department of the Army, the Department of the Navy and the Department of the Air Force.
Some other DOD groups include the the Missile Defense Agency, the National Geospatial-Intelligence Agency (NGA), the Defense Advanced Research Projects Agency (DARPA), the Pentagon Force Protection Agency (PFPA), the Defense Intelligence Agency (DIA) and the famed National Security Agency (NSA).
In terms of the department’s history, it was set up based on some specific plans drawn up by the Joint Chiefs of Staff and 19 December 1945, President Harry S. Truman proposed the creation of a new unified Department of National Defense. The proposal was mulled over and was eventually passed in 1947.
On July 26, 1947, Truman signed the National Security Act of 1947 which began the National Military Establishment which began active operations in September, 1947. The Establishment had the poorly thought out abbreviation NME which resembles ‘enemy’ and it was, in 1949, dubbed the DoD.
Until the creation of the DoD, US armed forces were separated into different departments which diluted any real central authority. The Marine Corps stayed a separate service under the Naval Department while the Coast Guard remained under the control of the Treasury Department.
The DoD’s budget was around 7 billion in 2007 though this figure does not include tens of billions more in spent on ‘supplementary’ things like nuclear weapons tests.
The DoD has authority over the Coast Guard in time of war. The Coast Guard is always considered one of the five branches of the US armed services, under the US Code. During times of declared war the Coast Guard works as a part 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 DoD is determined by the Goldwater-Nichols Act of 1986, made law by President Ronald Reagan in October, 1986. This Act modified the command structure of the United States military and it introduced the most significant changes to the Department since it was established.
According to the Act, the command structure 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 chiefly responsible for readiness of the US military and acts as the President’s chief military adviser while remaining outside of the chain of command.
