 Thors were removed from Johnston Atoll and were stored in mothballed war-reserve condition at Vandenberg Air Force Base from 1970 until the anti-satellite mission of Johnston Island facilities was ceased on August 10, 1974, and the program was officially discontinued on April 1, 1975, when any possibility of restoring the ASAT program was finally terminated.Eighteen Thor launches in support of the Program 437 Alternate Payload (AP) mission took place from Johnston Atoll's Launch emplacements.The Space Detection and Tracking System or SPADATS was operated by North American Aerospace Defense Command (NORAD) along with the U.S. Air Force Spacetrack system, The Navy Space Surveillance System and Canadian Forces Air Defense Command Satellite Tracking Unit.