The United States Air Force (USAF) is the aerial branch of the United States Armed Forces. Beginning as part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947.
The U.S. Coast Guard is one of the five armed forces of the United States and the only military organization within the Department of Homeland Security. The Coast Guard protects the maritime economy and the environment, defends our maritime borders, and saves those in peril.
The mission of the Department of Defense is to provide the military forces needed to deter war and to protect the security of our country. The department's headquarters is at the Pentagon.