USAF support activities began under the 7600th Air Base Group located in Madrid in July 1956, to support construction and base organizational functions. Torrejón Air Base opened officially on 1 June 1957 with SAC activating the 3970th Strategic Wing on 1 July 1957. The base hosting Sixteenth Air Force as well as SAC's 65th Air Division (Defense) where it cooperated with Spanish Air Force units in the Air Defense Direction Centers (ADDCs). The 65th Air Division directed base construction and the establishment of off-base housing and radar sites. The division's fighter squadrons flew air defense interceptions over Spanish airspace. The division also controlled the operations of numerous attached tactical fighter squadrons that were deployed to Spain for temporary duty (TDY). Assigned or attached units of the division participated in numerous exercises with the Spanish Air Defense Command, and in some instances, with the U.S. Sixth Fleet.