As early as Nov. 1961, President Kennedy approved the use of American herbicides in Vietnam, principally for defoliation--the destruction of vegetation (particularly jungle cover) that was being used to hide VC activity. In January, 1962, USAF aircraft--normally C-123 Providers equipped with spray tanks--began Operation Ranch Hand from Tan Son Nhut. By 1971, when the operation ended, 18 million gallons of chemicals had been dropped affectiong 5.5 million acres of South Vietnam as well as undisclosed portions of the Ho Chi Minh Trail in Laos and Cambodia.

A variety of herbicides, developed as weedkillers in the United States, were used. The most notorious was Agent Orange (named for the color of the drums it came in), which contained a growth hormone. Dropped onto trees, it accelerated their development, forcing them to shed their leaves prematurely, thus exposing trails or VC bases beneath to aerial view. Ranch Hand missions, preceded by leaflet drops to warn local peasants, usually involved two C-123s flying side by side to cover an area 250 yards either side of the target area.

At first, the U.S. government believed that Agent Orange was relatively harmless to human or animal life, and teams even went from village to village eating bread dipped in the chemical to show that it was not dangerous. But. in 1969, the U.S. National Cancer Institute discovered that one of its ingredients, dioxin, could cause cancer and possible birth defects. The effects are still being felt in Vietnam and also among those U.S. servicemen who came into contact with the chemical.

The devastating effect of the herbicides can be seen on what was once a mangrove forest.

U.S. aircraft (above and below) spray defoliant chemicals on Vietnam's jungle.