On the night that Lance Sijan disappeared, AWOL 01's target was Ban Loboy Ford, a river crossing on the Ho Chi Minh Trail, just inside Laos at the Ban Karai Pass. North Vietnam sent supplies and troops down the trail to sustain Viet Cong insurgents in the south. To interdict the flow, the Air Force struck convoys and choke points, such as Ban Loboy Ford and the mountain passes. They were heavily defended with anti-aircraft artillery.