Herbicidal warfare

Herbicidal warfare is the use of substances primarily designed to destroy the plant-based ecosystem of an area. Although herbicidal warfare use chemical substances, its main purpose is to disrupt agricultural food production and/or to destroy plants which provide cover or to the enemy, not to asphyxiate or poison humans and/or destroy human-made structures. Herbicidal warfare has been forbidden by the Environmental Modification Convention since 1978, which bans "any technique for changing the composition or structure of the Earth's biota".

Modern day herbicidal warfare resulted from military research discoveries of plant growth regulators in the Second World War, and is therefore a technological advance on the scorched earth practices by armies throughout history to deprive the enemy of food and cover.

Work on military herbicides 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 of biological warfare. Over 1,000 substances were investigated by the war's end for phytotoxic properties, and the Allies envisioned using herbicides to destroy Axis crops. British planners did not believe herbicides were logistically feasible against Germany.

In May 1945, USAAF General Victor E. Betrandias advanced a proposal to his superior General Arnold to use of ammonium thiocyanate to reduce rice crops in Japan as part of the bombing raids on their country. This was part of larger set of proposed measures to starve the Japanese. 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, then mustard gas would be an even more effective rice crop killer. The Joint Target Group rejected the plan as tactically unsound, but expressed no moral reservations.

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