United States Department of Defense - Organization

The Pentagon, in Arlington County, Virginia across the Potomac River from Washington, D.C., is the headquarters of the Department of Defense. The Department of Defense is protected by the Pentagon Force Protection Agency which ensures law enforcement and security for The Pentagon and various other jurisdictions throughout the National Capital Region (NCR). The Department includes the Army, Navy, Air Force, Marine Corps, as well as non-combat agencies such as the National Security Agency and the Defense Intelligence Agency. The DoD's annual budget was roughly $425 billion in 2006.[1] This figure does not include tens of billions more in supplemental expenditures allotted by Congress throughout the year, particularly for the war in Iraq. It also does not include expenditures by the Department of Energy on nuclear weapons design and testing.

In wartime, the Department of Defense has authority over the Coast Guard; in peacetime, that agency is under the control of the Department of Homeland Security (DHS). 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; the service has not been under the auspices of Navy since World War II, but members have served in the undeclared wars and conflicts since then while the service remained in its peacetime department.