The Air National Guard (ANG), often referred to as the Air Guard, is the air force militia organized by each of the fifty U.S. states, the commonwealth of Puerto Rico, the territories of Guam and the U.S. Virgin Islands, and the District of Columbia of the United States. Established under Title 10 and Title 32 of the U.S. Code, the Air National Guard is part of the state National Guard and is divided up into units stationed in each of the 50 states and U.S. territories and operates under their respective state governor or territorial government. The Air National Guard may be called up for active duty by the state governors or territorial commanding generals to help respond to domestic emergencies and disasters, such as those caused by hurricanes, floods, and earthquakes.

With the consent of state governors, members or units of the Air National Guard may be appointed, temporarily or indefinitely, to be federally recognized members of the armed forces, in the active or inactive service of the United States. If federally recognized, the member or unit becomes part of the Air National Guard of the United States, which is one of two reserve components of the United States Air Force, and part of the National Guard of the United States. Air National Guard of the United States units or members may be called up for federal active duty in times of Congressionally sanctioned war or national emergency. The President may also call up members and units of state Air National Guard, with the consent of state governors, to repel invasion, suppress rebellion, or execute federal laws if the United States or any of its states or territories are invaded or is in danger of invasion by a foreign nation, or if there is a rebellion or danger of a rebellion against the authority of the federal government, or if the President is unable with the regular armed forces to execute the laws of the United States. Because both state Air National Guard and the Air National Guard of the United States relatively go hand-in-hand, they are both usually referred to as just Air National Guard.