About Agent Orange

Why Agent Orange?

From 1961 to 1971, the U.S. government sprayed 20 million gallons of herbicides and defoliants, 12 million of which were Dioxin-contaminated Agent Orange, over Vietnam, large areas of Laos and parts of Cambodia.

During the time of the Vietnam War, dipterocarp forests, plantations, mangroves, brush lands, and other woody vegetation covered around 25 million acres of southern Vietnam, an area approximately the size of Vermont, New Hampshire and Massachusetts combined.

U.S. Air Force C-123 aircraft flew thousands of missions that sprayed the herbicides, as part of a defoliation program called “Operation Ranch Hand.” Their official objective was to defoliate, that is, to clear forests and destroy enemy crops. Fitted with specially developed spray tanks with a capacity of 1,000 gallons of herbicide, the C-123s could spray an 8.5-mile swath of land in less than five minutes. A smaller portion of the spraying efforts was also conducted by on-ground combatants by hand and by way of trucks out of U.S. military installations by the U.S. Army Chemical Corps and other allied forces.

The defoliation of the jungle cover and destruction of cropland was caused by the phenoxy herbicides, 2,4-D and Dioxin-contaminated 2,4,5-T, found in equal amounts in Agent Orange. Earlier in the war the US used Agents Purple, Pink and Green that also contained 2,4,5-T that was heavily contaminated with Dioxin.  Other herbicides used in Operation Ranch Hand were Agent White, a mixture of 2,4-D and picloram and Agent Blue, an arsenical herbicide used against rice crops that consisted of sodium cacodylate and cadodylic acid. It is worth noting that while the herbicides degraded and disappeared from the environment not long afterwards, Dioxin’s half-life is extremely long, varying according to what type of soil or sediment in which it is left. In the sediments of lakes, for instance, the half-life of dioxin can be as long as a century.

U.S. Objectives in Viet Nam

When U.S. President John F. Kennedy came into office in January 1961 the question of what to do with Vietnam had been answered. By May—the Cold War inevitably, and reductively, becoming the lens through which U.S. foreign policy was interpreted—President Kennedy reached a decision on U.S. objectives in Vietnam. The U.S. would “prevent communist domination of South Viet Nam,” a now-declassified White House memorandum read, “to create a viable and increasingly democratic society, and to initiate, on an accelerated basis, a series of mutually supporting actions of a military, political, economic, psychological, and covert character to achieve this objective.”

The U.S. shortly established the Combat Development and Test Center in Saigon, to identify new counterinsurgency techniques, along with the development of tactical weapons, against the North Vietnam Army and pro-Independence forces in the south. Among what was determined to be prime competitive advantages of these enemies was subsistence living under the cover of the thick jungle canopy, and so an herbicide powerful enough to clear this tropical-agricultural landscape was quickly becoming appealing.

Within months, in August 1961, after Dinoxil herbicide reached the shores of South Vietnam, defoliation testing began in Kontom Province.

The defoliation program started out small and nearly ended before it began as the efficacy of herbicide spraying as part of the U.S. war effort had been questioned by the Department of Defense, the State Department and the South Vietnamese government. Washington was also weary about a public backlash, both domestically and around the world, and that the program would be co-opted by the North Vietnamese as an anti-American propaganda tool. But President Kennedy was not swayed, agreeing instead with U.S. Secretary of Defense Roswell Gilpatric that the U.S. should “participate in a selective and carefully controlled joint program of defoliant operations in Vietnam starting with the clearance of key routes and proceed thereafter to food denial.”

President Kennedy also defended the use of tactical chemical herbicides as not violating “any rule of international law concerning the conduct of chemical warfare,” as a precedent “established by the British during the emergency in Malaya in their use of helicopters for destroying crops by chemical spraying.” The official stance at the time was that the use of herbicides, which did not target human populations, was akin to its agricultural use. Little was known about the extent of Dioxin contamination in the herbicides

On January 13, 1962, the first official Operation Ranch Hand mission flew over National Route 15, which stretched from the port of Vũng Tàu to Bien Hoa Air Base. As the American involvement in Vietnam escalated, so too did the use of herbicides. Operation Ranch Hand in Vietnam expanded to include large areas of south-eastern Laos in December 1965 and reached its peak by 1967 when over 1.5 million acres were sprayed by 1967.


“If we think they’re winning, you can imagine what they think.”
– President Lyndon Johnson, in a telephone conversation with Senator Mike Mansfield, 1965

The Apparent End

While opposition to the defoliation program existed from the very beginning it did not grow in strength until 1967 when the Federation of American Scientists—with more than 5,000 signatures of renowned scientists, 17 Nobel Laureates and 129 members of the National Academy of Sciences—submitted a petition to the White House. The American scientific community continued to raise concerns about the ecological and human impacts of the herbicides and conducted field investigations in Vietnam under the auspices of the American Association for the Advancement of Science.

Even Senator Robert Kennedy famously warned: “At the end of it all, they may say, as Tacitus said of Rome: ‘They made a desert, and called it peace.’”

In 1969 a study found that the herbicide 2,4,5-T caused birth defects in mice at high doses. A follow-up study in 1970 found what the chemical companies already knew that the 2,4,5-T herbicidal component in the 12 million gallons of Agent Orange was contaminated with 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD). These findings led to the US decision to restrict the use of of Agent Orange in Vietnam and the U.S.  Although the U.S. EPA did not formally ban the use of 2,4,5-T the U.S. until 1979.  Further studies have found TCDD to cause adverse health effects and birth outcomes. In 1997, the International Agency for Research on Cancer (IARC), part of the World Health Organization, classified TCDD as a known human carcinogen.

The last defoliation mission using Agent Orange took place in April 1970 however it was used for perimeter spraying of U.S. bases for the next six months. The Air Force flew its last official crop spraying mission using Agent Blue on January 7, 1971. Although, the South Vietnamese forces continued spraying the remaining stocks of Agent White and Blue until 1972.

In September 1971, the surplus inventories of tactical Agent Orange, including those under the control of the Armed Forces of South Vietnam, were re-barreled as part of the operation code-named “Pacer IVY” at Da Nang, Bien Hoa and Tuy Hoa airbases and shipped to Johnston’s Island in the South Pacific until it could be determined how to dispose of the chemicals. The 860,000 gallons of surplus Agent Orange in the US was shipped to the Seabees base in Gulfport, Mississippi where it was stored until 1977.  The Agent Orange was destroyed during “Operation Pacer Ho” when the 2.3  million gallons of Agent Orange from Gulfport and Johnston Island were incinerated in the South Pacific Ocean on the Vulcanus.

“Operation Ranch Hand” became a footnote in most accounts of the war in Vietnam, but its widespread use of Agent Orange and other herbicides, its toxic legacies, are still felt today.


Inside the Barrels: Agent Orange, Blue and White

Video Map of Spraying of Herbicides 1963-70. Developed by Jeanne Stellman.