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Poison Gas in Vietnam

Sometime early in 1964 the Pentagon asked the State Department to investigate and prepare a memo on the legality of the use of non-lethal gases in South Vietnam. The Pentagon’s point of view already was known: Army Field Manual 27-10, Law of Land Warfare, says “the United States is not a party to any treaty, now in force, that prohibits or restricts the use in warfare of toxic or non-toxic gases, or smoke or incendiary materials, or of bacteriological warfare.”

The State Department has traditionally been skeptical about the use of CBW agents; the United States had been one of the principals of the 1925 Geneva Conference which outlawed the use of asphyxiating, poisonous, or other gases.1 Nevertheless, the State Department eventually sent the Defense Department a memo agreeing that the non-lethal agents were legal. The State Department memo, however, contained a long list of stringent limitations on such use.

State made a mistake,” an official familiar with the situation told me three years later, “by saying it was okay—with limitations.” So far as the men in the Pentagon were concerned, “It was either yes or no: they [the State Department] were just kidding themselves with the restrictions.” The lesson of all this, the official said, “is that when the crunch comes, the Pentagon sets the requirements and State finds the reasons why it’s legal.”

The United States apparently began equipping the South Vietnamese Army with two of its three standard riot control, or non-lethal, gases in 1962 under the existing Military Assistance Program (MAP). The agents were CN, the standard tear gas used to quell civil disorders, and CS, the newly developed super tear gas. The third riot control agent, DM (adamsite), a nausea-producing gas, apparently did not reach Vietnam until 1964.

The military’s riot control gases are described by Army field manuals as agents that “produce temporary irritating or disabling physiological effects when in contact with the eyes or when inhaled. Riot control agents used in field concentration do not permanently injure personel.” The gases are actually solids that are disseminated as aerosols via grenades. Modern military chemical research has made little contribution to this aspect of the war arsenal; both CN and DM were invented in the latter days of World War I, and CS was reportedly developed by the British in the 1950s and adapted for United States use.

CN’S chemical name is chloroacetrophenone and its formula usually is given as C6H6COCCH2C1. It has a deceptive, fragrant odor similar to that of apple blossoms. The gas is a fast-acting tear agent that is also an irritant to the upper respiratory passages. An Army manual, Military Chemistry and Chemical Agents (TM 3-215), makes these further points:

In higher concentrations it is irritating to the skin and causes a burning and itching sensation, especially on moist parts of the body. High concentrations can cause blisters. The effects are similar to those of sunburn, are entirely harmless and disappear in a few hours. Certain individuals experience nausea following exposure to CN.

CS (the S stands for super) is chemically known as o-chlorobenzalmalononitrile. Its formula is ClC6H4CHC(CN3). TM 3-215 lists the following physiological effects:

CS produces immediate effects even in low concentrations…. The onset for incapacitation is 20 to 60 seconds and the duration of effects is 5 to 10 minutes after the affected individual is removed to fresh air. During this time the affected individuals are incapable of effective concerted action. The physiological effects include extreme burning of the eyes accompanied by copious flow of tears, coughing, difficulty in breathing, and chest tightness, involuntary closing of the eyes, stinging sensations of moist skin, running nose, and dizziness or swimming of the head. Heavy concentrations will cause nausea and vomiting in addition to the above effects.

DM, or adamsite, initially developed by the Germans in World War I, is the most toxic of the riot control agents. Its chemical name is diphenylaminochloroarsine and its formula is NH(C6H4)2 ASCl. The AS in the formula is arsenic. The pepper-like gas causes these symptoms in progressive order, according to TM 3-215: “Irritation of the eyes and mucous membranes, viscous discharge from the nose similar to that caused by a cold, sneezing and coughing, severe headache, acute pain and tightness in the chest and nausea and vomiting…. At higher concentrations, the effects may last up to three hours.”

Army Field Manual 3-10, Employment of Chemical and Biological Agents, lists DM, CS and CN together as riot control agents, a somewhat misleading category. In Chemicals in War, a history of gas warfare written in 1937 by Brigadier General Augustin M. Prentiss of the Chemical Warfare Service, CN is listed as a simple tear gas agent and DM is listed separately as a respiratory irritant. Prentiss had this to say about DM’s toxicity:

One is not aware of breathing this gas until sufficient has been absorbed to produce its typical physiological effects. It irritates the nose and throat in concentrations as low as .00038 milligrams per liter and causes irritation of the lower respiratory tract at a concentration of .0005 mg. per liter. A concentration of .65 mg. per liter is lethal at 30 minutes’ exposure while the lethal concentration for 10 minutes is 3 mg. per liter.

Put another way, Prentiss’s statistics mean that DM is lethal upon 10 minutes’ exposure to the gas in concentrations of 1/10,000 of an ounce per quart of air.

THE ARMY has been combining DM and CN in a grenade for use in Vietnam. “Since DM requires several minutes to produce maximum effects, it may be combined with CN to produce effects more rapidly,” explains FM 3-10. The manual adds this word of caution:

DM alone is not approved for use in riot control dispersers in any operations where deaths are not acceptable. Excessive, and possibly lethal, or completely incapacitating dosages can be developed from its use. However, it may be used in military or paramilitary operations, on counterinsurgency operations, or in limited or general war where control of target personnel by the incapacitating effects is desired and where possible deaths are acceptable.

The South Vietnamese, acting on their own initiative, used CF and CN to break up a Buddhist riot in Saigon on November 2, 1964. By the next month the South Vietnamese Army, guided by US advisers, initiated the use of DM, CF, and CN in military operations against the Viet Cong. In missions carried out in strictest secrecy, the munitions were used on December 23 in Xuyen province, on December 25 in Tay Ninh province near Saigon, and on January 28, 1965, in Phu Yen province.

On March 22, 1965, Horst Faas, an Associated Press reporter tagging along on a combat mission near Saigon, learned that the operation plans called for the use of DM if the government forces were pinned down by the Viet Cong. He was told that the agent caused vomiting and diarrhea. No enemy contact was made during the mission and Faas returned to Saigon to report what he had heard and seen. The news service carried on its teletypes the next day a story revealing that the United States was “experimenting” with gas warfare. This was subsequently confirmed in Washington and Saigon.

What Faas saw set off a worldwide protest that apparently caught US policy-makers by surprise. The White House, State Department, and Pentagon each responded to the controversy by arguing, in effect, that there was nothing unusual in the use of riot control gases. But US officials took unusually elaborate steps that March 23 to get their point across to the press and public. McNamara quickly summoned Pentagon newsmen to his office, described the three gases in detail, and made it clear that the United States had no intention of stopping their use against Viet Cong guerrillas. He emphasized that the gases were similar to those used by police forces around the world to curb civil disturbances, and listed a number of such uses. McNamara did not mention that adamsite is rarely used by police anywhere.

Secretary of State Dean Rusk made an unusual appearance at the regular daily noon briefing at the State Department to deny that the United States was embarking on the use of gas warfare in Vietnam. “We are not talking about agents or weapons that are associated with gas warfare, the military arsenals of many countries [sic],” he told the reporters. “We are not talking about gas that is prohibited by the Geneva Convention of 1925, or any other understanding about the use of gas.”

Rusk, too, emphasized that the agents used were gases available commercially, and said it was anticipated that “these weapons be used only in those situations involving riot control or situations analogous to riot control.” He admitted that the United States may have committed a major propaganda blooper, not by using the gases, but by attempting to hold back public knowledge of the new step. “It may be that there was a failure in full explanation, in briefing or reporting from Saigon on this matter,” Rusk allowed, adding that the initial AP story tended to stimulate problems “which were not present—for example the use of the word ‘experimentation’ suggested that something new and weird might be involved here. That is not the case.”

At the White House, Press Secretary George Reedy went to elaborate steps to disassociate President Johnson from the use of nausea gas. He said the President had not been consulted about its use and described adamsite as a “rather standard-type riot-control agent.” Reedy said full responsibility for its use depended on General William C. Westmoreland, commander of the US forces in Saigon.

The American use of gas was condemned throughout the world: a Frankfurt newspaper published a cartoon showing the Statue of Liberty wearing a gas mask; Mainichi Shimbun, one of Japan’s largest newspapers, carried a cartoon of Adolf Hitler’s ghost hovering over Vietnam with a bag labeled “Vietnam” in his right hand. In New York, the Times, in a sharply critical editorial, pointed out that “in Vietnam, gas was supplied and sanctioned by white men against Asians. This is something that no Asian, Communist or not, will forget. No other country has employed such a weapon in recent warfare.”

The Soviet Union took the issue to the United Nations, where it accused the United States of grossly violating “the accepted rules of international law and of the elementary principles of morality and humanity. The US Government is, of course, aware that the use of asphyxiating, poisonous or other gases has long since been prohibited and vigorously condemned by the peoples of the world.” Similar Soviet charges were made in a note delivered to the US Embassy in Moscow. The United States replied, in a letter to the President of the UN Security Council, that the Soviet note had been rejected because it “was based on the completely false allegation that poisonous gases are being used in South Vietnam….” The US note went on to describe the chemicals used in Vietnam as non-toxic and not prohibited by the 1925 Geneva Protocol as interpreted by the United States.

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    The US delegation signed the treaty but the Senate Foreign Relations Committee refused to ratify it in 1926 after a rare closed-door debate. Thirty-two nations eventually adhered to the Protocol which was violated only once before 1964, when Italy used mustard gas against Ethiopia in the Abyssinian Campaign of 1936. The United States has consistently expressed its support of the 1925 agreement, and has publicly acknowledged it considers itself bound in full by it. Moreover, the US and ninety-five other nations voted during a little-noticed UN General Assembly meeting in December, 1966, to reaffirm the principles of the Geneva Protocol. Most international lawyers argue that the United States, whether it agreed or not, is bound by the Protocol simply because it has acted as if it had signed the agreement; this opinion is held by many in the State Department.

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