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Herbicidal warfare is the use of substances primarily designed to destroy the plant-basedecosystem of an area. Although herbicidal warfare usechemical substances, its main purpose is to disruptagricultural food production and/or to destroy plants which provide cover or concealment to the enemy, not toasphyxiate orpoison humans and/or destroy human-made structures. Herbicidal warfare has been forbidden by theEnvironmental Modification Convention since 1978, which bans "any technique for changing the composition or structure of the Earth'sbiota".[1]
Modern day herbicidal warfare resulted frommilitary research discoveries ofplant growth regulators duringWorld War II, and is therefore a technological advance on thescorched earth practices by armies throughout history to deprive the enemy of food and cover. Work on militaryherbicides began in England in 1940, and by 1944, the United States joined in the effort. Even though herbicides are chemicals, due to their mechanism of action (growth regulators), they are often considered a means ofbiological warfare. Over 1,000 substances were investigated by the war's end forphytotoxic properties, and theAllies envisioned using herbicides to destroyAxis crops. British planners did not believe herbicides were logistically feasible againstNazi Germany.
In May 1945,United States Army Air Force commanderGeneral Victor Betrandias advanced a proposal to his superior, GeneralHenry H. Arnold, to use ofammonium thiocyanate to reduce Japaneserice crops part of Alliedair raids on Japan. This was part of larger set of proposed measures to starve the Japanese in submission. The plan calculated that ammonium thiocyanate would not be seen as "gas warfare" because the substance was not particularly dangerous to humans. On the other hand, the same plan envisaged that if the U.S. were to engage in "gas warfare" against Japan, thenmustard gas would be an even more effective rice crop killer. TheJoint Target Group rejected the plan as tactically unsound, but expressed no moral reservations.[2]
During theMalayan Emergency,British Commonwealth forces deployedherbicides anddefoliants in the Malaysian countryside in order to depriveMalayan National Liberation Army (MNLA) insurgents of cover, potential sources of food and to flush them out of the jungle. The herbicides and defoliants they used containedTrioxone, an ingredient which also formed part of the chemical composition of theAgent Orange herbicide used by theU.S. military during theVietnam War. Deployment of herbicides and defoliants served the dual purpose of thinning jungle trails to prevent ambushes and destroying crop fields in regions where the MNLA was active to deprive them of potential sources of food. In the summer of 1952, 500 hectares were sprayed with 90,000 liters of Trioxone fromfire engines; British Commonwealth forces found it difficult to operate the machinery in jungle conditions while wearing full protective gear. Herbicides and defoliants were also sprayed fromRoyal Air Force aircraft.[3]
Historical records ofDOW chemical show that "Super Agent Orange", also called DOW Herbicide M-3393, was Agent Orange that was mixed withpicloram. Super Orange was known to have been tested by representatives fromFort Detrick and DOW chemical in Texas, Puerto Rico, and Hawaii and later in Malaysia in a cooperative project with the International Rubber Research Institute.[4] Discussions in theBritish government centered on avoiding the thorny issue of whether herbicidal warfare in Malaya was in violation of the spirit of the 1925Geneva Protocol, which only prohibited chemical warfare among signatory states in international armed conflicts. The British were keen to avoid accusations like theallegations of biological warfare in the Korean War leveled against the United States. The British government found that the simplest solution was to deny that a conflict was going on in Malaya. They declared the insurgency to be an internal security matter; thus, the use of herbicidal agents was a matter of police action, much like the use ofCS gas for riot control.[3]
Many Commonwealth personnel who handled herbicides and defoliants during, and in the decades after, the conflict suffered from serious exposure to dioxin, which also led tosoil erosion in areas of Malaysia. Roughly 10,000 civilians and insurgents in Malaysia also suffered from the effects of the defoliant, though many historians argue the true number was higher given that herbicides and defoliants were used on a large scale in the Malayan Emergency; the British government manipulated data and kept its deployment of herbicidal warfare secret in fear of a diplomatic backlash.[5][6][7]
TheUnited States used herbicides inSoutheast Asia during theVietnam War. Success withProject AGILE field tests with herbicides in South Vietnam in 1961 and inspiration by the British use of herbicides and defoliants during the Malayan Emergency led to the formal herbicidal programOperation Trail Dust (1961–1971).Operation Ranch Hand, aU.S. Air Force program to useC-123K aircraft to spray herbicides over large areas, was one of many programs under Trail Dust. The aircrews charged with spraying the defoliant used a sardonic motto-"Only you can prevent forests"-a shortening of theU.S. Forest Services famous warning to the general public "Only you can prevent forest fires". The United States and its allies officially claims that herbicidal andincendiary agents likenapalm fall outside the definition of "chemical weapons" and that Britain set the precedent by using them during the Malayan Emergency.
Ranch Hand started as a limited program of defoliation of border areas, security perimeters, and crop destruction. As the conflict continued, the anti-crop mission took on more prominence, and (along with other agents) defoliants became used to compel civilians to leaveViet Cong-controlled territories for government-controlled areas. It was also used experimentally for large area forest burning operations that failed to produce the desired results. Defoliation was judged in 1963 as improvingvisibility in jungles by 30–75% horizontally, and 40–80% vertically. Improvements in delivery systems by 1968 increased this to 50–70% horizontally, and 60–90% vertically. Ranch Hand pilots were the first to make an accurate 1:125,000 scale map of theHo Chi Minh trail south ofTchepone,Laos by defoliating swaths perpendicular to the trail every half mile or so.
Use of herbicides in Vietnam caused a shortage of commercial pesticides in mid-1966 when theDefense Department had to use powers under theDefense Production Act of 1950 to secure supplies. The concentration of herbicides sprayed in Operation Ranch Hand was more than an order of magnitude greater than that in domestic use. Approximately 10% of the land surface of South Vietnam was sprayed—about 17,000 square kilometers. About 85% of the spraying was for defoliation and about 15% was for crop destruction.[8]
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The United States had technical military symbols for herbicides that have since been replaced by the more common color code names derived from the banding on shipping drums. The US further distinguished betweentactical herbicides, which were to be used in combat operations and commercial herbicides, which used in and around military bases, etc.[9]
In 1966 theUnited States Defense Department claimed that herbicides used in Vietnam were not harmful to people or the environment. In 1972 it was advised that a known impurity precluded the use of these herbicides in Vietnam and all remaining stocks should be returned home. In 1977 theUnited States Air Force destroyed its stocks ofAgent Orange 200 miles west ofJohnston Island on the incinerator shipM/T Vulcanus. The impurity,2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was a suspectedcarcinogen that may have affected the health of over 17,000United States servicemen, 4,000Australians, 1,700New Zealanders,Koreans, countlessVietnamese soldiers and civilians, and with over 40,000 children of veterans possibly suffering birth defects from herbicidal warfare.
Decades later the lingering problem of herbicidal warfare remains as a dominant issue ofUnited States-Vietnam relations. In 2004, a coalition of Vietnamese survivors and long-term victims of Agent Orangesued a number of American-based and multinational chemical corporations for damages related to the manufacture and use of the chemical. A federal judge rejected the suit, claiming that the plaintiff's claim of direct responsibility was invalid due to it not being recognized as a poison in the legal sense at the time, thus the U.S. was not prohibited from using it as a herbicide.[10][11]
