Air Defense Artillery

The Air Defense Artillery branch of the US Army specializes in anti-aircraft weapons (such as surface to air missiles). In the US Army, these groups are composed of mainly air defense systems such as the Patriot Missile System, Terminal High Altitude Area Defense (THAAD), and the Avenger Air Defense system which fires the FIM-92 Stinger missile. The Air Defense Artillery branch descended from Anti-Aircraft Artillery (part of the U.S. Army Coast Artillery Corps until 1950, then part of the Artillery Branch) into a separate branch on 20 June 1968. On 1 December 1968, the ADA branch was authorized to wear modified Artillery insignia, crossed field guns with missile.

Anti-aircraft warfare or counter-air defence is defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground-and air-based weapon systems, associated sensor systems, command and control arrangements and passive measures (e.g. barrage balloons). It may be used to protect naval, ground, and air forces in any location. However, for most countries the main effort has tended to be 'homeland defence'. NATO refers to airborne air defence as counter-air and naval air defence as anti-aircraft warfare. Missile defence is an extension of air defence as are initiatives to adapt air defence to the task of intercepting any projectile in flight.