In 1962, U.S. Special Forces established a camp in the far northwest corner of South Vietnam at the village of Khe Sanh. The camp stood only ten and a half miles east of the Laotian border and seventeen miles south of the Demilitarized Zone (DMZ) separating North from South Vietnam. To ensure the air delivery of supplies and reinforcements to the garrison stationed there, American engineers built a simple dirt airstrip atop the Xom Cham Plateau, a height of flat, red earth bordered on the north and west by dark-green, forested peaks. Off the eastern end of the airstrip, the plateau abruptly fell away into a chasm eroded by the waters of the Rao Quan River.
Khe Sanh’s Special Forces “A” Team and Montagnard Strike Force (known as Strikers), patrolled the nearby jungles to intercept Vietcong “returnees” (those guerrillas returning south of the 17th parallel after having regrouped to North Vietnam following the 1954 Geneva Accords) and North Vietnamese regulars, who entered South Vietnam over a system of well-trodden infiltration routes.
One infiltration route came down from the DMZ, entered the Cam Lo River Valley, and then ran southeasterly before passing a steep mountain that one day in the not-too-distant future would be famous among the U.S. Marines as the “Rock Pile.” A second trail ran south from the DMZ along a small stream named the Khe Ta Bong. A third infiltration route darted eastward from the Laotian border, passed north of Khe Sanh village, crossed the Rao Quan River, and then skirted south of the Rock Pile along the Khe Trinh Hin Valley. There existed numerous other trails northwest of the Special Forces camp, one of the more prominent tracks extended east-southeast from Lang Pelo, Laos. This trail had a number of small offshoots running to the south and east.
In 1964, the Green Berets moved the site of their camp from Khe Sanh village to the Xom Cham Plateau. The Americans considered the plateau site more defensible in the event of a large-scale North Vietnamese attack, which by that stage in the war had become a real possibility as thousands of Communist troops began moving down the Ho Chi Minh Trail to tip the military balance in the South irrevocably in favor of the Vietcong. The new site also eased the resupply of the Green Berets. Airlifted cargo no longer had to be transported down the narrow dirt road from the plateau to the camp.
The Green Berets and Montagnard Strikers at Khe Sanh failed to halt the movement of infiltrators into South Vietnam for the same reasons they had been unsuccessful elsewhere. Rugged terrain, thick vegetation, and uncooperative weather conditions worked against their efforts. Plus, unreliable Montagnards, the absence of light observation planes and reconnaissance helicopters, the small number of foot soldiers engaged in active patrolling at any one time, and the large land area requiring constant surveillance doomed the anti-infiltration program from the start.
The terrain surrounding Khe Sanh made interdiction almost impossible. The rivers and streams of the Central Highlands ran through deep, dark valleys, which impeded Allied ground observation. For example, only a mile east of the Khe Sanh camp, the Rao Quan River flowed through one of the Central Highlands’ countless, steep-sided valleys. From atop the plateau, an observer could not see the bottom of the Rao Quan. As a result, Communist troops could get right under the nose of the base’s garrison without observation.
Prominent hills and high ridges stood close to the Khe Sanh base camp. Hills 881 North, 881 South and 861 (the numerical designation specified their height in meters) gained notoriety in 1967 and 1968.
Hills 950 and 1015 stood directly north of the base on the other side of the Rao Quan. A high ridgeline, running west to east, joined the two promontories. Peering north from the airstrip, the rocky mass of Hills 950 and 1015 resembled an enormous green wall. At dusk, the stone monolith turned a forbidding black.
The headlands around Khe Sanh gave Communist spotters a clear view of the base and its occupants. The Green Berets and Monty Strikers were under constant surveillance from the hills above or from the Vietcong spies inside the base who posed as loyal Montagnards. The Vietcong usually knew when American-led patrols departed the base, their planned line-of-march, and their ultimate tactical objective. Employing radios or runners, the Vietcong forewarned their comrades moving down the Ho Chi Minh Trail of the approach of Allied patrols. Consequently, U.S.-led patrols rarely found the guerrillas or North Vietnamese regulars.
Triple-canopy jungle, tall elephant grass, and dense bamboo stands added to the troubles of Allied recon teams. A green cloak of vegetation concealed Communist infiltrators. Surveillance was made more difficult by fog, rain, and clouds. Fog descended on the camp and its environs daily during the northeast monsoon season from September through January. At night and in the early morning hours, ghostly fingers of fog slid down from the mountain heights, completely covering the valleys and low-lying areas. These were the same places through which Communist troops marched in silence through the impenetrable haze. The fog usually retreated between 9:30 am and 11:00 am, having been burned off by the piercing Indochinese sun and the rising temperatures of mid-day.
Rain had the same effects on visibility as fog – it masked the whereabouts of the Vietcong and North Vietnamese, grounded U.S. helicopters and reconnaissance aircraft, and reduced the visual range of the naked eye. Rain also muffled or completely drowned out the sound of a footfall or whispered voice.
During the northeast monsoon, a fine mist – known to the French as “crachin” – fell from the sky for days on end. Low, wispy clouds and chilly temperatures accompanied the crachin. The worst time of the year to operate out of Khe Sanh was the December to February period, when clouds and crachin enveloped the base, literally blinding its garrison. Locating the Vietcong and North Vietnamese at that time of the year was like trying to find a needle in a haystack with the lights turned off.
Route 9 linked the base to South Vietnam’s coastal plain. Since the mid-1940s, and the outbreak of the First Indochina War, the road had been subjected to regular Communist ambush. A long row of high hills stood over the roadway between Khe Sanh and Ca Lu; while immediately south of the dirt track flowed the Thach Han River. At several locations, Route 9 came within feet of the river’s edge. The road – flanked by hills on the north and by the river to the south, offered no wiggle room for an Allied convoy under attack. In order to shut down traffic on Route 9, the Communists simply needed to destroy one of the many bridges west of Cam Lo.
Between 1962 and early 1968, the Vietcong and North Vietnamese repeatedly closed Route 9, forcing the Americans to resupply the Green Berets and Strikers at Khe Sanh and Lang Vei (another Special Forces camp located 3.5 miles southwest of Khe Sanh) by air. But air resupply frequently fell victim to the vicissitudes of the South Vietnamese environment. The same clouds, crachin, and fog that hampered the surveillance missions of the Special Forces recon teams grounded cargo planes.
Khe Sanh possessed one other major tactical handicap. Namely, Communist centers of power in North Vietnam and Laos sat only a short distance away. Tchepone, Laos, a North Vietnamese transportation, communications, and logistics hub, sat only thirty-three miles west of the base, or about a day and a half of hard marching by Communist foot soldiers. And troop staging areas within North Vietnam lay only about twenty-five miles north of the camp. Consequently, Communist commanders could rapidly move large infantry units against Khe Sanh from either Laos or North Vietnam.
Khe Sanh’s disadvantageous terrain, difficult weather, tenuous connection to the coast via Route 9, and the ease with which the North Vietnamese Army could send sizable forces against its defenders should have raised serious doubts in Washington and Saigon about sending the U.S. Marines to hold the base.
 New York Times, “Foe’s Laos Build-up Reported Taxing U.S. Bomber Forces,” Charles Mohr, January 17, 1968; New York Times, “Confrontation at Khe Sanh,” February 18, 1968.
 New York Times, “Khe Sanh Shelled Under Fog Cover,” Charles Mohr, January 26, 1968.
 New York Times, “5,000 Men Massed at Khesanh by U.S.,” Charles Mohr, January 24, 1968.