The Air National Guard's federal mission is to maintain well-trained, well-equipped units available for prompt mobilization during war and provide assistance during national emergencies (such as natural disasters or civil disturbances). During peacetime, the combat-ready units and support units are assigned to most Air Force major commands to carry out missions compatible with training, mobilization readiness, humanitarian and contingency operations such as Operation Enduring Freedom in Afghanistan. Air National Guard units may be activated in a number of ways as prescribed by public law. Most of the laws may be found in Title 10 of the U.S. Code.
The Air National Guard provides almost half of the Air Force's tactical airlift support, combat communications functions, aeromedical evacuations and aerial refueling. In addition, the Air National Guard has total responsibility for air defense of the entire United States.