Operation Commando Hunt - Igloo White

Igloo White

As early as 1966 Secretary of Defense Robert S. McNamara had become increasingly disenchanted with the bombing of the north. No amount of pressure, it seemed, could either drive Hanoi to the negotiating table or slow the flow of PAVN supplies and men to the south. He then began to consider an alternative in the form of a physical strongpoint/electronic barrier to infiltration that would stretch below the Demilitarized Zone from the coast to the Laotian frontier (and possibly beyond). This was the origin of the so-called "McNamara Fence."

The physical barrier was to be backed up by air-dropped and hand-emplaced acoustic and seismic sensors that would provide both warning and location of enemy movements. A scientific group was established to find or develop the technology for what was initially titled Practice Nine. On 17 June 1967 the title of the program was altered to Illinois City and on 15 July to Dyemarker, the electronic barrier portion of which was designated Muscle Shoals. In June 1968 it was renamed for the last time, becoming Operation Igloo White.

Igloo White consisted of three interrelated parts. The battery-operated sensors would be monitored by an airborne command and control center (ABCCC), which would relay the information to an Infiltration Surveillance Center (ISC), located at Nakhon Phanom, Thailand. Computers at the ISC would collate and analyze the data and then relay target coordinates to the ABCCC which would, in turn, direct strike aircraft to the targets. The hand emplacement of sensors and bomb damage assessment missions were to be carried out by the reconnaissance teams of the highly classified Military Assistance Command, Vietnam Studies and Observations Group (SOG), which already operated "over the fence" in Laos. Construction began on the ISC on 6 July 1967 and was completed within three months.

The anti-infiltration effort would be supported by MSQ-77 Combat Skyspot, a ground-based radar bombing system first introduced in Southeast Asia in 1966 to direct B-52 strikes in poor weather or in complete darkness. This system was utilized to direct one-quarter of all strike missions conducted by U.S. aircraft during the conflict. Combat Skyspot was complemented by expanding the radio-based LORAN system utilized by other strike aircraft.

A shakedown of the system took place during the first two weeks of November 1967 and it seemed to work. The PAVN siege against U.S. Marines at the Khe Sanh Combat Base, in western Quang Tri Province, South Vietnam, provided the opportunity for an operational test. The American command in Saigon launched Operation Niagara, the largest tactical and B-52 operation thus far in the conflict, to support the Marines at Khe Sanh. By the end of January 1968, Muscle Shoals had emplaced 316 sensors in 44 strings to detect North Vietnamese troop movements in the vicinity of the combat base. The operation was deemed a success, but locating and targeting enemy troops moving toward a fixed location like Khe Sanh was not the same as doing it on the Ho Chi Minh Trail.

And there were already problems with the system. The anti-personnel portion of the program had already failed. The presence and movements of enemy troops were to be detected by the utilization of small, wide-area Gravel mines that were to alert the acoustic sensors. Unfortunately, the mines rapidly deteriorated in the heat and humidity of Laos, nullifying their effectiveness. The focus of any interdiction campaign, therefore, would have to concentrate on PAVN supply transportation. The war against trucks was about to begin.