A series examining contentious issues of the Vietnam War

One frequently debated question of the Vietnam War concerns North Vietnam’s motive for laying siege to the U.S. Marine Corps base at Khe Sanh in northwestern Quang Tri province just south of the Demilitarized Zone and about 10 miles from Laos.

Actually, North Vietnam had several motives, some rarely discussed in the literature of the war. Hanoi had short-term, medium-term and long-term reasons for besieging Khe Sanh, a conclusion drawn from both American sources and postwar Vietnamese histories.

The short-term goal for the siege, which began Jan. 21, 1968, was to provide a diversion for the communists’ Tet Offensive, which would strike all across South Vietnam the night of Jan. 30-31. The North Vietnamese Army’s 304th and 325th divisions closed in around the Khe Sanh base in early January, ringing alarm bells through Washington.

The base was defended by a mere two battalions from the 26th Marine Regiment. It was accessible only by air and not well-fortified. Gen. William C. Westmoreland, the top U.S. commander in Vietnam, ordered the 3rd Battalion from the 26th Marines and some supporting forces to Khe Sanh immediately.

When the siege began, the ferocity of the rocket and mortar attacks deepened President Lyndon B. Johnson’s anxiety. Determined not to let the garrison fall like the French base at Dien Bien Phu had to a communist-led independence movement in 1954, Johnson ordered Westmoreland to take all necessary measures to protect Khe Sanh.

The South Vietnamese rushed several airborne battalions to Quang Tri province—exactly what Hanoi wanted. Those airborne battalions were among the best units in the South Vietnam’s army and the most likely to thwart the coming communist attacks on Saigon and other big cities.

The North Vietnamese never expected to overrun Khe Sanh, but they wanted to put on a convincing show. However, the siege prompted Westmoreland to move two brigades of the 1st Cavalry Division (Airmobile) into Quang Tri and neighboring Thua Thien province.

The 1st Cav units played decisive roles in defeating Tet attacks there. On balance, the Khe Sanh diversion backfired for the communists, tying down the better part of two North Vietnamese divisions in the critical first days of Tet.

In its medium-term motive for the siege, Hanoi hoped to lure allied forces into western Quang Tri province, ambushing them as they pushed west on the rutted and partly washed-out Highway 9. This plan also turned out badly.

When allied forces initiated Operation Pegasus on April 1, 1968, to lift the siege of Khe Sanh, the North Vietnamese were rotating units there and had only part of one division in place. Short on manpower, the North Vietnamese could do little to stop the airmobile 1st Cavalry Division from leapfrogging over their blocking positions and reopening Highway 9.

North Vietnam’s long-term motive for eliminating Khe Sanh stemmed from its concern that the U.S. and South Vietnam might use the base as a staging area for a cross-border operation into Laos to cut the Ho Chi Minh Trail. Those fears were well-founded. Westmoreland and his successor, Gen. Creighton Abrams, intended to launch such an operation in late 1968, but never received the authority to do so. V

Dr. Erik Villard is a Vietnam War specialist at the U.S. Army Center of Military History at Fort McNair in Washington D.C.

This article appeared in the April 2021 issue of Vietnam magazine. For more stories from Vietnam magazine, subscribe here and visit us on Facebook: