United States Department of Defense (DOD) and the Pentagon

department of defense

Overview of the United States Department of Defense

The United States Department of Defense (DOD or sometimes listed as DoD) is the federal department responsible for coordinating and supervising all agencies and functions of the government relating directly to national security and the military. The organization and functions of the Department of Defense are set forth in Title 10 of the United States Code.

The Department of Defense is the major tenant of The Pentagon building near Washington, D.C., and has three major components:

  • The Department of the Army
  • The Department of the Navy
  • Department of the Air Force

Related Agencies

Among the many Department of Defense agencies are:

  • The Missile Defense Agency
  • The Defense Advanced Research Projects Agency (DARPA)
  • The Pentagon Force Protection Agency (PFPA)
  • The Defense Intelligence Agency (DIA)
  • The National Geospatial-Intelligence Agency (NGA)
  • The National Security Agency (NSA)

Training Academies

The department also operates several joint service schools and training academies, including the National War College. Following are military training academies sponsored by the DOD:

Department Websites

  • United States Department of Defense Website – United States Department of Defense website. Includes the latest news and issues the department is dealing with. Provides a list of all DOD sites and other resources.

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The Pentagon: The United States Department of Defense Headquarters

The Pentagon is the headquarters of the United States Department of Defense and is located in Arlington, Virginia. “The Pentagon” is often used to refer to the Department of Defense rather than the building itself.

The Pentagon was designed by the American architect George Bergstrom (1876 – 1955).  The Pentagon was built by Philadelphia, Pennsylvania, general contractor John McShain.  The Pentagon building was dedicated on January 15, 1943, after ground was broken for construction on September 11, 1941.

The Pentagon Reservation

The Pentagon Reservation is located in southeastern Arlington County, Virginia, and is situated between a large man-made lagoon (the Pentagon Lagoon, formed during construction) and the southeastern corner of Arlington National Cemetery. The northeastern and eastern facades have unobstructed vistas of the Monumental Core of the Nation’s Capital across the Potomac River. The Pentagon’s relatively low profile also permits clear vistas of Washington from the highlands of Arlington National Cemetery. The Pentagon is the world’s largest office building by floor area, with about 6,500,000 sq ft (604,000 m2), of which 3,700,000 sq ft (344,000 m2) are used as offices.  The Pentagon building is twice the size of the Merchandise Mart in Chicago, Illinois and has three times the floor space of the Empire State Building in New York.

The U.S. National Capitol could fit into any one of the five wedge-shaped sections. Approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel work in the Pentagon.  The Pentagon has five sides, five floors above ground (plus two basement levels below ground), and five ring corridors per floor with a total of 17.5 miles of corridors.

The building includes a five-acre central plaza, which is shaped like a pentagon and informally known as “ground zero”, a nickname originating during the Cold War and based on the presumption that the Soviet Union would target one or more nuclear missiles at this central location in the outbreak of a nuclear war.

The Pentagon Official Website – Provides information on the Pentagon, the history of the Pentagon, Pentagon tour booking information, facts and figures, and more.

List of Defense Agencies

  • Defense Advanced Research Projects Agency (DARPA) – Seeks to advance knowledge through research and create innovative technologies that address current problems.
  • Defense Commissary Agency (DECA) – Operates a worldwide chain of commissaries (basically military grocery stores) that provide groceries to military personnel, retirees and their families.
  • Defense Contract Audit Agency (DCAA)
  • Defense Contract Management Agency (DCMA)
  • Defense Information Systems Agency (DISA)
  • Defense Information Systems Agency (DISA)
  • Defense Intelligence Agency (DIA)
  • Defense Legal Services Agency (DLSA)
  • Defense Logistics Agency (DLA)
  • Defense Security Cooperation Agency (DSCA)
  • Defense Security Service (DSS)
  • Missile Defense Agency (MDA)
  • National Geospatial-Intelligence Agency (NGA)
  • National Security Agency (NSA)
  • Pentagon Force Protection Agency (PFPA)


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