Poison Gas in Vietnam

Lyndon Johnson
Lyndon Johnson; drawing by David Levine

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…

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