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Why Agent Orange?

Between 1961 and 1971, the U.S. sprayed 12 million gallons of Dioxin-contaminated Agent Orange and 8 million gallons of other herbicides on Vietnam and large areas of both avowedly neutral Laos and Cambodia.

Operation Ranch Hand

U.S. Air Force C-123s flew 20,000 missions that sprayed the herbicides as part of the defoliation program code-named Operation Hades, later renamed Operation Ranch Hand. During the war, 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 program’s official objective was to deploy tactical code-named “Rainbow herbicides” that could denude this tropical-agricultural landscape, which provided cover and subsistence for counterinsurgency forces.

The U.S. deployed Agents Orange, Purple, Pink, and Green, in its ecocidal war. Each of these agents contained varying concentrations of the phenoxy chemical 2,4,5-T, which was contaminated with Dioxin. The toxicity of Agent Orange, above the other herbicides, was attributed to its equal mixture of Dioxin-contaminated 2,4,5-T and another phenoxy chemical 2,4-D. Other herbicides included 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 cacodylic acid. Much of the herbicides used during Operation Ranch Hand were up to 50 times the concentration recommended for killing plants.

Fitted with specially developed spray tanks with a capacity of 1,000 gallons of herbicides, C-123s were able to spray an 8.5-mile swath of land in less than five minutes. A smaller portion of spraying was also conducted by ground combatants at U.S. military installations, under the supervision of the U.S. Army Chemical Corps and other allied forces.

U.S. Objectives in Vietnam

When U.S. President John F. Kennedy came into office in January 1961, the question of what to do with Vietnam was still unanswered. But by May of that same year, the Cold War inevitably becoming the lens through which U.S. foreign policy was interpreted—President Kennedy made a decision on U.S. objectives in Vietnam: To “prevent communist domination of South Vietnam,” 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 study new counterinsurgency techniques and develop tactical weapons to use against the North Vietnam Army and pro-Independence forces in the south. The U.S. determined the cover of the thick jungle canopy to be one of the enemy’s prime competitive advantages, and moved to develop herbicides that were powerful enough to denude Vietnam’s tropical-agricultural landscape.

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

The defoliation program started out small and nearly ended before it began as the the Department of Defense, the State Department, and the South Vietnamese government questioned the efficacy of the herbicide. Washington was also wary 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. The U.S. would remain on its path to “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.”

Moreover, the official White House stance on the use of herbicides was that it did not violate “any rule of international law concerning the conduct of chemical warfare,” a precedent “established by the British during the emergency in Malaya.” It was also argued that the use of herbicides, which did not target human populations, was akin only to its agricultural use domestically. Little was known at the time about the byproduct of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), also known as Dioxin, that occurred during the accelerated industrial manufacturing of the herbicides and the extent of subsequent 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 southeastern Laos, in December 1965, and reached its peak by 1967 when over 1.5 million acres were sprayed.

“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 submitted a petition to the White House. More than 5,000 renowned scientists, 17 Nobel Laureates, and 129 members of the National Academy of Sciences implored President Kennedy to halt the program, but with no effect.

The U.S. 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 Dioxin-contaminated 2,4,5-T was teratogenic, meaning that at high doses it caused birth defects in mice. A follow-up study a year later 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 Dioxin. These findings led to the U.S. decision to restrict the use of Agent Orange altogether, though the U.S. EPA did not formally ban the use of 2,4,5-T until 1979. Later studies eventually found that Dioxin also caused adverse health effects and birth outcomes in humans. In 1997, the International Agency for Research on Cancer (IARC) of the World Health Organization, classified TCDD as a “known human carcinogen.”

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

In September 1971, the surplus inventories of 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 air bases. The barrels were then shipped to Johnston’s Island in the South Pacific until it could be determined how they would be disposed of. Meanwhile the 860,000 gallons of surplus Agent Orange in the U.S. were shipped to the Seabees base in Gulfport, Mississippi, where it was stored until 1977. Then, in that same year, about 2.3 million gallons of Agent Orange from Gulfport and Johnston Island were incinerated in the South Pacific Ocean on the Vulcanus, as part of “Operation Pacer Ho.”

“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.


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