The Environmental Impact of Agent Orange

Ecocidal warfare


During the time of the U.S. war in Vietnam, dipterocarp forests, plantations, mangroves, brush lands, and other woody vegetation constituted about 25 million acres of dense tropical forests in South Vietnam, an area approximately the size of the state of Kentucky.

The way it was: Da Lat Forest 1950

It was this tropical-agricultural landscape, which provided cover and subsistence for counterinsurgency forces in key areas, that became a primary target of the U.S. and its allied forces. The U.S. developed tactical herbicides that would denude the forest and destroy agricultural lands; and for ten years, between 1961 and 1971, the U.S. Air Force flew nearly 20,000 spray missions, deploying about 20 million gallons of these herbicides over southern Vietnam and the verdant landscape, along the Ho Chi Minh Trail in Laos, and parts of Cambodia. Much of the herbicides used in the spray missions, contaminated with Dioxin, were up to 50 times the concentration recommended for killing plants.


The aerial spraying of herbicides allowed for easy application, causing aberrant growth and death of certain plant species, over large areas of land.

This intentional defoliation of the jungle canopy and destruction of cropland ultimately disrupted the ecological equilibrium of Vietnam, Laos, and Cambodia. It was as Senator Robert Kennedy said: “At the end of it all (…) they may say, as Tacitus said of Rome: ‘They made a desert, and called it peace.’”

More than five million acres of forests and agricultural lands were sprayed at least once, approximately 10 percent of the total land area of southern Vietnam, and about 20 percent of the enemy-occupied forest cover.  About 15 percent of the spray runs that mainly used Agent Blue targeted agricultural lands that accidentally damaged both enemy and civilian food sources. This oversight in the anticrop program triggered widespread famine, leaving thousands of people malnourished or severely food insecure. Over 600,000 gallons of Agent Orange and other herbicides were sprayed along the Ho Chi MInh Trail in Southern Laos. Cropland was also targeted with Agent Blue in central Laos.

The loss of a significant proportion of southern Vietnam‘s forest cover triggered a number of related effects. For example, loss of timber led to reduced sustainability of ecosystems, decreases in the biodiversity of plants and animals, poorer soil quality, increased water contamination, heavier flooding and erosion, increased leaching of nutrients and reductions in their availability, invasions of less desirable plant species (primarily woody and herbaceous grasses), and possible alterations of both macro- and micro-climates.”

— Wayne Dwernychuk, the Hatfield Group

The Natural Environment.

After the Planes Came

About 10 percent of the trees sprayed died from a single spray run. But within two to three weeks of spraying, trees en masse began losing their leaves. These trees remained bare until the next rainy season. In order to defoliate the lower stories of forest cover, the U.S. Air Force conducted follow-up spraying missions. Multiple sprayings, in addition to incendiaries and heavy carpet bombing, resulted in increased mortality in trees.

Among the trees that died from single spraying were the mangroves in the Delta region, the most sensitive of trees. Approximately 259,000 acres of mangroves were sprayed, with about one-third of the mangroves vital to the coastal ecology damaged or entirely destroyed. Of the upland forests sprayed, the hardest hit were the dense forests of Ma Da, Phu Binh, Sa Thay, A Luoi and along Route 19.

Ecological Warfare or Ecocide

A minimum of 20 million cubic meters of timber were destroyed, though other estimates range as high as 90 million. The destruction was so great that the terms “ecological warfare” and “ecocide” were coined, and frequently invoked, to describe what took place in the war’s aftermath.

In areas where deforestation and subsequent degradation of the forest occurred, invasive species of grasses, Pennisetum polystachyon and Imperata cylindrica, which the Vietnamese call “American grass,” took over.

Natural regeneration of the forest was not possible as there were not enough trees to produce viable seedlings. There was also no longer a layer of trees with enough integrity to protect the vulnerable seedlings from the harsh sun. Moreover, the defoliation of lands resulted in the depletion of soil nutrients and in large-scale erosion, especially in the mountainous regions affecting 28 river basins in south Vietnam.

“Trees are our enemy.”

– American Army commander as told to photographer Philip Jones Griffiths

After the war was over, the Vietnamese focused on replanting the mangrove forests along the coastlines in order to protect these sensitive ecological regions vital for flood control. The heavily deforested regions in the highlands were much more difficult to address. Secondary deforestation occurred as the valuable trees that did remain after the spraying were harvested. Years of hot sun turned the clay soils into laterite, making reforestation challenging.

Unable to bring back the triple canopy forests in the highlands, efforts were made to plant single species of eucalyptus and acacia trees in the deforested regions. Although the hillsides are for the most part now covered in vegetation, these single species forests are not conducive to generating biodiversity.

Jungle Removed
Viet Nam: War’s Lasting Legacy

Viet Nam: War’s Lasting Legacy

A presentation by Phung Tuu Boi, Boi Center for Assistance in Nature Conservation and Community Development, Vietnam and advisor to the Vietnam Victims of Agent Orange Association (VAVA).