The McNamara Line was an unofficial name for a defensive project initiated by the United States between 1966 and 1968 during the Vietnam War to prevent infiltration of South Vietnam by NVA forces from North Vietnam and Laos. The McNamara Line ran across South Vietnam from the South China Sea to the Laotian border along the Vietnamese Demilitarized Zone (DMZ). It included fortified field segments with Khe Sanh as linchpin, along with open spaces, where road and trails were guarded by the high-tech acoustic and heat-detecting sensors on the ground and interdicted from the air. A sophisticated electronic surveillance was backed with gravel mines and troops at choke points. Named the barrier system by Robert McNamara, it was one of the key elements, along with gradual aerial bombing, of his wa