The attack on Khe Sanh, which began on 21 January, may have been intended to serve two purposes—as a real attempt to seize the position or as a diversion to draw American attention and forces away from the population centers in the lowlands, a deception that was “both plausible and easy to orchestrate.” In General Westmoreland’s view, the purpose of the Combat Base was to provoke the North Vietnamese into a focused and prolonged confrontation in a confined geographic area, one which would allow the application of massive U.S. artillery and air strikes that would inflict heavy casualties in a relatively unpopulated region. By the end of 1967, MACV had moved nearly half of its maneuver battalions to I Corps in anticipation of just such a battle.
Westmoreland—and the American media, which covered the action extensively—often made inevitable comparisons between the actions at Khe Sanh and the Battle of Điện Biên Phủ, where a French base had been besieged and ultimately overrun by Viet Minh forces under the command of General Giáp during the First Indochina War. Westmoreland, who knew of Nguyen Chi Thanh’s penchant for large-scale operations—but not of his death—believed that this was going to be an attempt to replicate that victory. He intended to stage his own “Dien Bien Phu in reverse.”
Khe Sanh and its 6,000 U.S. Marine Corps, Army, and ARVN defenders was surrounded by two to three North Vietnamese divisions, totaling approximately 20,000 men. Throughout the siege, which lasted until 8 April, the allies were subjected to heavy mortar, rocket, and artillery bombardment, combined with sporadic small-scale infantry attacks on outlying positions. With the exception of the overrunning of the U.S. Special Forces camp at Lang Vei, however, there was never a major ground assault on the base and the battle became largely a duel between American and North Vietnamese artillerists, combined with massive air strikes conducted by U.S. aircraft. By the end of the siege, U.S Air Force, Marine Corps, and Navy aircraft had dropped 39,179 tons of ordnance in the defense of the base.
The overland supply route to the base had been cut off, and airborne resupply by cargo aircraft became extremely dangerous due to heavy North Vietnamese antiaircraft fire. Thanks to innovative high-speed “Super Gaggles,” which utilized fighter-bombers in combination with large numbers of supply helicopters, and the Air Force’s utilization of C-130 Hercules cargo aircraft employing the innovative LAPES delivery method, aerial resupply was never halted.
When the Tet Offensive began, feelings ran high at MACV that the base was in for a serious attack. In I Corps, the Tet truce had been cancelled in apprehension of a communist assault that never happened. The offensive passed Khe Sanh by and the intermittent battle continued. Westmoreland’s fixation upon the base continued even as the battle raged around him in Saigon. On 1 February, as the offensive reached its height, he wrote a memo for his staff—which was never delivered—claiming that “The enemy is attempting to confuse the issue…I suspect he is also trying to draw everyone’s attention from the area of greatest threat, the northern part of I Corps. Let me caution everyone not to be confused.”
In the end, a major allied relief expedition (Operation Pegasus) reached Khe Sanh on 8 April, but North Vietnamese forces were already withdrawing from the area. Both sides claimed that the battle had served its intended purpose. The U.S. estimated that 8,000 North Vietnamese troops had been killed and considerably more wounded, against 730 American lives lost and another 2,642 wounded.