United States Department of Defense United States Department of Defense The Department of Defense (DoD, USDOD, or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government concerned directly with national security and the United States Armed Forces. The department is the largest employer in the world, with nearly 1.3 million active duty servicemen and women as of 2016. Adding to its employees are over 826,000 National Guardsmen and Reservists from the four services, and over 742,000 civilians bringing the total to over 2.8 million employees. Headquartered at the Pentagon in Arlington, Virginia,
Crystal City, Arlington, Virginia be renamed "National Landing", which encompasses not only Crystal City but also Pentagon City and Potomac Yard. Crystal City, Arlington, Virginia Crystal City is an urban neighborhood in the southeastern corner of Arlington County, Virginia, south of downtown Washington, D.C. Due to its extensive integration of office buildings and residential high-rise buildings using underground corridors, travel between stores, offices, and residences is possible without going above ground; thus, a large part of Crystal City is an underground city. Crystal City includes offices of numerous defense contractors, the United States Department of Labor, the United States Marshals Service and many satellite