The Air National Guard (ANG), also known as the Air Guard, is a federal military reserve force of the United States Air Force, as well as the air militia of each U.S. state, the District of Columbia, the Commonwealth of Puerto Rico, and the territories of Guam and the U.S. Virgin Islands. It, along with the Army National Guard component of each state, district, commonwealth or territory, makes up the National Guard of each region as applicable.
When Air National Guard units are used under the jurisdiction of the state governor they are fulfilling their militia role. However, when federalized by order of the president of the United States, ANG units become an active part of the U.S. Air Force. They are jointly administered by the states and the National Guard Bureau, a joint bureau of the Army and Air Force that oversees the U.S. National Guard.