McNamara Line

The McNamara Line was an operational strategy employed by the United States in 1966–1968 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). The eastern part included fortified field segments with Khe Sanh as linchpin, along with stretches, where roads 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 assorted types of mines, including gravel, 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 war strategy in Vietnam.

Barrier concept

Various schemes had been proposed in the years before 1965 for a defensive line on the northern border of South Vietnam and in southeast Laos. These schemes had generally been rejected because of their requirements for large amounts of military personnel to be deployed in static positions and because any barrier in Laos would encourage the Vietnamese to deploy their forces deeper into Laotian territory.