防空識別區
The 57th FIS at Keflavik was an interceptor squadron charged with the monitoring of the Greenland, Iceland, United Kingdom gap in the North Atlantic that formed a naval warfare choke point during the Cold War. The 57th would respond alerts from Ground-Control Intercept (GCI) and warning stations established on Iceland; the GCI stations guiding its interceptor aircraft toward unidentified intruders picked up on the radar scopes. Over 1,000 intercepts of Soviet aircraft took place inside Iceland's Military Air Defense Identification Zone (ADIZ).