Unlike the Americans, the North Vietnamese were unable to hold fixed positions due to the efficacy of allied firepower. As a result, the Communists concentrated on harassing and disrupting allied forces. The American military command concluded that the only way to stop the disruption was to destroy enemy forces in sufficient numbers. The American commanders hoped that at Khe Sanh they would be able to kill enemy troops in a ratio of 10 to 1, 20 to 1, or even 30 to 1. The Americans clung to their belief in the value of a positive kill ratio in face of compelling evidence showing they were mostly unable to achieve it. 

Despite the fact that Khe Sanh was encircled by enemy troops, the U.S. Defense Department claimed that the fortress blocked five avenues of infiltration from Laos into South Vietnam . According to the official view of the situation in February 1968, if Khe Sanh were abandoned, entire North Vietnamese divisions could "pour down Route 9 [the major east-west highway below the DMZ] and four other natural approaches through the valleys and could overrun a chain of Marine positions; the Rockpile, Con Thien, Dong Ha, and Phu Bai to the east." This would mean that the North Vietnamese could be in a good position to seize control of South Vietnam 's two northernmost provinces, Quang Tri and Thua Thien, with grave political and psychological consequences. 

This strategic rationale was secondary to the primary reason for holding onto Khe Sanh: Washington was unwilling to give its enemy a psychological victory by giving ground. One official source explained the basis for this reasoning by recalling the first Battle of Khe Sanh, fought in 1967. "We had to put our foot down, and for psychological and political reasons, we wouldn't want to pull back," said the official. "What would the newspapers have written if we had given up Khe Sanh afterward?" 

Another reason for holding Khe Sanh was its importance as the western anchor of the McNamara Line, a high-technology barrier designed to impede the flow of Communist troops and supplies into South Vietnam . The barrier was supposed to stretch from the South China Sea to the Laotian border. Secretary of Defense Robert McNamara hoped the barrier would allow the Americans to reduce their reliance on the bombing of North Vietnam , thereby increasing Washington 's flexibility in seeking a diplomatic settlement to the war. 

On February 25, General Westmoreland expressed doubt that the North Vietnamese could stand a long war. Responding to a question during an interview in Saigon about whether his fundamental strategy had been changed by the Tet Offensive, Westmoreland replied, "Basically, I see no requirement to change our strategy." 

The key to the defense of Khe Sanh was overwhelming air power. On March 27, senior Marine officers in Da Nang claimed that the effectiveness of allied airpower was so great that "they have no plans for pulling the Marines out no matter how much the enemy might increase his shelling at Khe Sanh." An Air Force spokesman said that since January 22, allied airmen had dropped 80,000 tons of ordnance around Khe Sanh. "We plan to keep up the pace indefinitely," he added. 

The same report noted that airpower had limited effectiveness. Even though 80,000 tons of ordnance amounted to more than the nonnuclear tonnage dropped on Japan throughout World War II, it had not stopped enemy movement around Khe Sanh. On March 25, a Marine patrol was halted by heavy enemy machine-gun and mortar fire after traveling only 100 to 200 yards past the camp's barbed wire perimeter. During the previous week, the enemy had managed to fire 1,500 rocket, artillery and mortar rounds at the Khe Sanh base. 

Other examples illustrate that the protective aerial umbrella around Khe Sanh was less that 100 percent effective. On February 8, enemy gunners fired hundreds of mortar rounds into a Marine position on nearby Hill 64. The NVA assault that followed the mortar barrage resulted in 21 men killed, 26 wounded and four Marines missing in action. Only one Marine on Hill 64 was unscathed. Colonel Lownds, the base commander, however, later described the Marine casualties resulting from the fighting on Hill 64 as "light." 

On February 25, a two-squad patrol, instructed not to venture farther than 1,000 meters from the base perimeter, vanished. Two weeks later, casualties of the so-called ghost patrol were established as nine dead, 25 wounded, and 19 missing. A company-size patrol on March 30 had as one of its missions the recovery of the bodies of the ghost patrol. This second patrol suffered three dead, 71 wounded and three missing before being ordered to pull back. Only two bodies from the ghost patrol were recovered at that time. 

On April 5, the 76-day siege was officially declared ended. Since 7,000 North Vietnamese were still reported to be in the vicinity of Khe Sanh, however, the end of the siege was more official than real. The North Vietnamese had fired more than 40,000 artillery, rocket, and mortar rounds into the Marine positions during the siege. 

By April, the situation had changed in the Khe Sanh area. The New York Times noted that the North Vietnamese had built several new roads into South Vietnam from Laos--apparently in an effort to improve their ability to move troops, heavy weapons and supplies into combat areas. Two of the new roads pushed across the South Vietnam­Laos border to the north and south of the Khe Sanh combat base. No longer would NVA troops have to endure protracted marches along the Ho Chi Minh Trail. They could be driven closer to the battlefield in trucks. Heavy weapons and ammunition could be transported to the front more quickly and in greater quantity. 

These new logistics capabilities had profound implications for American military commanders. General Westmoreland had built up the Marine force at Khe Sanh to approximately 6,000 men, a figure that represented a balance between the number that could be effectively supplied and the force level necessary to ensure adequate defense of the combat base. Since at that time the Marine garrison could only be supplied by air, any increase in the Communists' ability to launch attacks against the Marine positions could tip the balance against the Marines. 

According to a New York Times report dated May 24, both President Lyndon B. Johnson and General Westmoreland felt the decision to defend Khe Sanh was the proper one. They believed that the defense of the camp not only prevented the North Vietnamese from opening a major route into South Vietnam's populated areas, but also greatly strengthened the American initiative toward peace talks, "for they [the Marine defenders] vividly demonstrated to the enemy the utter futility of his attempts to win a military victory in the South," according to the New York Times. 

Although the level of fighting fell off in April, it was not over. On May 30, 600 NVA attacked Marines in their night defensive positions around Khe Sanh. The attack was supported by mortar, artillery and rocket fire. Marine losses were 13 killed and 44 wounded. Two days later another battle took place when a large NVA force attacked Marine positions two miles southeast of Khe Sanh. Two-hundred-thirty North Vietnamese were reported killed in that battle, in some of the heaviest fighting in South Vietnam at that time. 

In a June report, New York Times reporter Douglas Robinson described Khe Sanh as "still a fearsome place of exploding shells and death." North Vietnamese artillerymen fired 130mm artillery shells from caves or dug-in positions on the Co Roc massif in Laos . These guns, out of the range of the largest U.S. artillery, had been firing on Khe Sanh for months. It was difficult to prepare adequate defenses against them, since even dud rounds penetrated four feet into the ground. The Americans were unable to destroy these guns. In early June, the North Vietnamese gunners at Co Roc were still able to fire more than 100 rounds in a single day into the base at Khe Sanh. Marine Brig. Gen. Carl W. Hoffman claimed, "The North Vietnamese still want Khe Sanh and we are still trying to keep them from getting it." The general described the enemy as being composed of "fresh, well-equipped troops with new haircuts and good morale, proof we are facing not a rabble but well-trained force." 

In the six weeks preceding that June report, the Marines had killed about 1,300 North Vietnamese Army regulars within a four-mile radius of Khe Sanh. During that time, American dead and wounded had flowed in a steady stream to the Khe Sanh aid station, which was dug deep into the ground. General Hoffman conceded that the Communists had the ability to keep the Khe Sanh combat base under pressure for "as long as they wished." 

Months earlier, the Marines had made an effort that, had it been successful, would have given them means to counter the threat posed by the NVA heavy artillery at Co Roc. In August 1967, a large supply convoy left Dong Ha for Khe Sanh, including several U.S. Army 175mm self-propelled guns. General Westmoreland had wanted to position the guns at Khe Sanh to deal with NVA artillery in Laos . When the convoy ran into an enemy ambush along Route 9, however, the decision was made to deploy the large guns at Camp Carroll rather than risk their destruction at the ambush site.

That incident caused a change in thinking about resupply for Khe Sanh. Route 9 was too risky; thereafter, during the period from August 1967 until Route 9 was reopened in April 1968, Khe Sanh would be resupplied by air. The reopening of the road was accomplished through Operation Pegasus, a combined Marine and Army sweep of Route 9 to the combat base. 

With the arrival of the relief column, an Army colonel replaced Colonel Lownds as base commander. Army troops would replace the Marines, freeing them to go on the attack. Although ending the siege freed the beleaguered Marines for offensive operations, it also gave increased flexibility to the enemy forces. No longer would they have two divisions tied down at Khe Sanh. Even though a large portion of the NVA force withdrew into Laos near the DMZ, they could easily be shifted to other battlefields as needed. One American official claimed the North Vietnamese withdrawal had been prompted by the effectiveness of the American bombing campaign. The U.S. military command refused to say definitely whether it planned to keep American troops at Khe Sanh. However, since the purpose of the base had been to serve as a center for anti-infiltration activity before the siege, some senior officers hinted that a continued American presence at Khe Sanh was likely. 

The reopening of Route 9 to convoy traffic did not mean that the supply problem had been solved. These convoys faced the same threats that they had in 1967. American units had to be stationed at every bridge and culvert to guard against ambushes. Steep cliffs lined the roadway, making it possible for the enemy almost to drop grenades into passing trucks. Supplies moving overland were threatened by almost nightly ambushes and firefights. 

One June 16, Marines reported a North Vietnamese attack on Marine positions south of Khe Sanh, in which 168 Communist soldiers were killed. Although the fighting continued, the U.S. command felt significant changes had taken place around Khe Sanh. Friendly strength, mobility and firepower, had increased since the Army forces had arrived, but the extent of the enemy threat had increased due to a greater flow of replacements and a change in NVA tactics. Consequently, the base at Khe Sanh was to be abandoned. 

Senior Marine commanders had long felt that maintaining a large force at Khe Sanh was more of a liability than an asset. They had only garrisoned the place because of pressure from General Westmoreland. In late 1967, an Army task force was formed to control activity in this critical sector of South Vietnam ; Westmoreland felt the Marines were unable to adequately direct the battle. In March, Army Lt. Gen. William B. Rosson took command of the task force. Unknown to General Westmoreland, Rosson and his Marine counterpart, Lt. Gen. Robert E. Cushman, decided on their own in April to withdraw American forces from Khe Sanh. 

Naval gunfire experts and Air Force liaison officers were sent to Khe Sanh to plan for the destruction of the Marine positions. Marines began packing their equipment and filling in foxholes. The base chaplain at Khe Sanh noted in his diary, "The general attitude of people in the base is that it is wrong to abandon the base after fighting so long for it." 

When Westmoreland found out about Rosson and Cushman's plan, a Marine general on Westmoreland's staff in Saigon claimed that he "never saw Westy so mad." The Marines at Khe Sanh were notified that the base would not be abandoned. They began unpacking their personal gear and started digging in again. 

Marines would continue to occupy Khe Sanh and various nearby hill positions and engage in search and destroy missions. Fresh Marine and Army units would replace the Marines who had spent the siege at Khe Sanh. More than 400 American troops would be killed and 2,300 wounded in the 10 weeks following the end of the siege. Those figures were more than two times the casualties sustained by the Marines in the siege during the period from late January to late March. 

On June 11, 1968 , General Westmoreland relinquished his command of U.S. forces in Vietnam . The Rosson-Cushman plan to abandon the base, previously rejected by Westmoreland, was to be implemented. This version of the plan was dated the day after Westmoreland turned control over to his successor, Army General Creighton W. Abrams. The Marines who had fought at Khe Sanh were furious, with one of the battalions "almost in open revolt" over the decision.  

ARTICLE WRITTEN BY PETER BRUSH