Ground-controlled interception (GCI) an air defense tactic whereby one or more radar stations[citation needed] are linked to a command communications centre which guides interceptor aircraft to an airborne target. This tactic was pioneered during World War II by the Royal Air Force with the Luftwaffe to follow closely. Today, GCI is still important for most nations, although Airborne Early Warning and Control, with or without support from GCI, tends to be more capable and flexible.[citation needed]