In the War


While almost all of the 20 million gallons of herbicides were sprayed in southern Vietnam, the U.S. war effort spilled over into avowedly neutral Laos, where significant spraying had also occurred. Little is known about the present-day consequences of the spraying there.

Flight records taken from the HERBS database show that spray missions flown on 209 dates, between 1965 and 1970, sprayed a total of at least 537,495 gallons of tactical herbicides. The heaviest spraying began in early 1966 and continued at a steady rate until February 1967, after which the rate of spraying became intermittent until October 1970. For over five years, these spray runs were coordinated out of Bien Hoa air base, with some also out of Ton San Nhat and Da Nang, in Vietnam.

Savannakhet, Salavan, Sekong and Attapeu provinces, all abutting Vietnam’s southwestern border, covered an area of Laos territory where the Ho Chi Minh Trail had extended into from Vietnam. These southeastern provinces in Laos were the most heavily sprayed; Khammouane province, to the north of Savannakhet, and Champasak province, to the southwest by Cambodia, were also sprayed, but comparatively less so.

As in Vietnam, the herbicides were used not only to defoliate forests, but also to destroy crops. Records from Military Assistance Command Vietnam (MACV) show that 64 crop destruction missions (an area a total of 32 square miles along the Ho Chi Minh Trail) took place between September 1966 and September 1969. The spraying and heavy bombing forced villagers to flee to the hills for up to ten years. The food supply chain was inevitably upended as a result, triggering an immense loss of crops and livestock that was followed by malnutrition lasting decades, even after the war.

According to William Buckingham’s history of Operation Ranch Hand, the U.S. Air Force sprayed 419,850 gallons—of which, 75 percent were Agent Orange, 15 percent Agent Blue, and 10 percent Agent White—over 255 square miles of Laos, up until September 1969.

Like the bombing of Laos during the war, the use of herbicides in Laos was secretive until 1982, when a draft of Buckingham’s study of Operation Ranch Hand was made public. Much about the U.S. war effort in Laos is still classified.

Very little is known about spraying that may have been done under the auspices of the U.S. CIA; nor is it known if there was any hand or helicopter spraying done on bases controlled by the U.S. or allied forces. For a very short time in 1968 Air America used one of its Porter aircraft to spray Agent Orange in central Laos. Technical issues with the spray nozzles made this impractical, however.

In 2019, the U.S. Department of Defense released a list of where herbicides were used outside of Vietnam. It states that Agent Orange was stored and loaded onto planes at Udorn Air base in Thailand between October 1968 and September 1969 and used for “missions flown in northern Laos.” What shows up on the HERBS database are three spraying missions, which were conducted over an area approximately 60 miles northeast of Vientiane, the capitol city of Laos, in September 1969.

The complete account of the use of herbicides in Laos has yet to surface, though a survey conducted by War Legacies Project to determine the impact of aerial spraying of herbicides in Laos is underway.


La Bang Khok, Savannakhet. near a major storage depot along the Ho Chi Minh Trail. Old North Vietnamese fuel barrels put to good use.