By Andrew Wells-Dang, Expanded version

In contrast to the widespread spraying of herbicides in Laos and South Vietnam over a long period, one instance of defoliation in Cambodia resulted in a major international incident. This attack took place on French- and Cambodian-owned rubber plantations in Kampong Cham province from April 18-May 2, 1969, at a time when the US had no diplomatic relations with the government of then-Prince Norodom Sihanouk. The damage caused was substantial. Both US Government and independent inspection teams
confirmed that 173,000 acres were sprayed (7% of Kompong Cham province), 24,700 of them seriously affected.

The rubber plantations totaled approximately one-third of Cambodia’s total and represented a loss of 12% of the country’s export earnings. The mystery surrounding the attack has to do with who exactly carried it out. Cambodia was officially neutral in the Vietnam War, though the eastern part of its territory had been subject to infiltration by both US Special Forces (“Operation Daniel Boone”) and
guerrillas on southern portions of the Ho Chi Minh Trail.

No herbicides were admitted to be used, however, and large-scale US operations in Cambodia would not begin until the April 1970 covert invasion. The available evidence points to Air America, the primary air contractor for the CIA.

Once the extent of the damage in Kampong Cham became apparent, Cambodian authorities made a formal complaint to the US. It was not the first time. Cambodia had made allegations of chemical warfare against the US beginning in 1964; when any US response was given, it was always to deny that any attacks occurred.

An American Quaker who was in Cambodia at the time notes, however, that the mechanism for
compensating farmers for spray damage appeared to be well-established and routine,
suggesting that similar incidents had happened previously.

A declassified memo from the US Embassy in Saigon stating that “Past experience shows [Cambodian] protests [of chemical warfare] are not always accurate” begs the question of which protests were, in
fact, true.