Organizational structure of the United States Department of Defense 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; this has not happened since World War II, but members have served in undeclared wars and conflicts since then while the service remained in its peacetime department. The Pentagon, in Arlington County, Virginia, across the Potomac River from Washington, D.C., is the Department's headquarters. The Department is protected by the Pentagon Force Protection Agency, which
Arlington County, Virginia in the county, while 86% commute in, with 27% commuting from Fairfax County. An additional 92,784 people commute out for work, with 42% commuting to DC, and 29% commuting to Fairfax County. A number of federal agencies are headquartered in Arlington, including the Air Force Office of Scientific Research, American Battle Monuments Commission, DARPA, Diplomatic Security Service, Drug Enforcement Administration, Foreign Service Institute, the DHS National Protection and Programs Directorate, Office of Naval Research, Transportation Security Administration, United States Department of Defense, United States Marshals Service, and the United States Trade and Development Agency. Companies headquartered in Arlington include AES,