During this period, the 1968 Tet Offensive was underway in South Vietnam, the Marine outpost at Khe Sanh Combat Base was under siege, and there existed an unprecedented flow of enemy logistical traffic which had to be interdicted. Lima Site 85 had provided direction to about a quarter of the USAF missions over North Vietnam and Barrel Roll from November 1967 to 11 March 1968.
During this time, the Tet Offensive was happening in South Vietnam, Khe Sanh Combat Base was under siege, and there was an unusual amount of enemy supply traffic that needed to be stopped. Lima Site 85 had directed about a quarter of the USAF missions over North Vietnam, and Barrel Roll was used from November 1967 to March 11, 1968.