United States Department of Defense

The United States Department of Defense (DOD), also referred to as the Department of War (DOW), is an executive department of the United States federal government charged with coordinating and supervising the United States Armed Forces—the Army, Navy, Marines, Air Force, Space Force, and, for some purposes, the Coast Guard—and related functions and agencies. Headquartered at the Pentagon in Arlington County, Virginia, just outside Washington, D.C., the stated mission of the Department of Defense is "to provide the military forces needed to deter war and ensure our nation's security".

The Department of Defense is headed by the secretary of defense, a cabinet-level official who reports directly to the president of the United States. The president is commander-in-chief of the U.S. Armed Forces. Within the Department of Defense are three subordinate military departments: the Department of the Army, the Department of the Navy, and the Department of the Air Force. In addition, four national intelligence services are part of the Department of Defense: the Defense Intelligence Agency, National Security Agency (NSA), National Geospatial-Intelligence Agency, and National Reconnaissance Office.

Other agencies in the Department of Defense include the Defense Advanced Research Projects Agency (DARPA), Defense Logistics Agency, Missile Defense Agency, Defense Health Agency, Defense Threat Reduction Agency, Defense Counterintelligence and Security Agency, Space Development Agency and Pentagon Force Protection Agency. Additionally, the Defense Contract Management Agency is responsible for administering contracts for the Department of Defense. Military operations are managed by eleven regional or functional unified combatant commands. The Department of Defense also operates several joint services schools, including the Eisenhower School and the National War College.

the department has over 1.4 million active-duty uniformed personnel in the six armed services, and over 747,000 civilian employees. It also supervises over 778,000 National Guard and reservist personnel. Provided by Wikipedia