The Department of Defense is responsible for providing the military force and resources needed to deter war and to protect the security of the United States. It maintains its headquarters at the Pentagon in Washington. The department operates through the business transformation and defense commissary, logistics and contract audit agencies. The Department of Defense administers the U.S Army, U.S. Air Force, Marine Corps, U.S. Navy, U.S. National Guard and U.S. Coast Guard. Its Defense Advanced Research Projects Agency (DARPA) is responsible for maintaining the technological superiority of the U.S. military through research and development activities. The department also operates the National Security Agency/ Central Security Service, which focuses on providing foreign signals intelligence information and protecting the national security systems.