air defense

Anti-aircraft warfare (AAW) or air defence is the counter to aerial warfare and includes "all measures designed to nullify or reduce the effectiveness of hostile air action". It encompasses surface-based, subsurface (submarine-launched), and air-based weapon systems, in addition to associated sensor systems, command and control arrangements, and passive measures. 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