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Did the U.S. use nerve gas during OPERATION TAILWIND in 1970?
Mustard: An Ambiguous Term
Vaccinations Against Anthrax for U.S. Forces

Did the U.S. use nerve gas during OPERATION TAILWIND in 1970?
Harvey J. McGeorge
Public Safety Group
June 24, 1998

During a June 7th CNN NewsStand report and a subsequent article in TIME magazine it was asserted that on or about 13 and 14 September 1970, U.S. Air Force aircraft dropped munitions containing the nerve agent Sarin (GB) on or around a village in Laos. These munitions were reportedly employed in support of OPERATION TAILWIND and were intended to prepare the village for attack and subsequently cover the withdrawal of U.S. forces.

Our position is that the incident did not occur as reported. Further, it is our belief that nerve agents were not used as described but that the use of the riot control agent CS was likely. Our contribution to the review of this incident will be a description of the agents and munitions potentially involved and an analysis of the reported incident from their perspective.

President Nixon prohibited the use of nerve agents by U.S. forces. In a statement on 25 November 1969 President Nixon said "… the United States reaffirms its oft-repeated renunciation of the first use of lethal chemical weapons." Sarin is a nerve agent intended for tactical use as a lethal agent in field concentrations. The use of Sarin, if it occurred, would appear to be a violation of the policy set forth by the President. President Nixon could have authorized the use of lethal chemical agents if he had found that such chemicals had been used against U.S. forces. No such presidential finding has been reported.

The reports specifically mention the CBU-15 munition. The acronym CBU refers to Cluster Bomb Unit. CBUs consist of a SUU (Suspension and Release Unit) which contains multiple BLUs (Bomb Live Unit). Numerous SUUs were developed and fielded along with over 100 different BLUs. In a number of cases a specific BLU could be used with more than one SUU. Each combination of SUU and BLU had a specific CBU model number. The CBU-15 was a U.S. Air Force dispenser munition intended for use with either high (jet) or low (propeller) performance aircraft. The CBU-15 consisted of the SUU-13 underwing dispenser and 40 Sarin filled BLU-19 submunitions.

The SUU-13 dispenser is approximately 100 inches long, 15 inches wide and 14 inches high. It is generally rectangular in shape and had rounded nose and tail fairings. The SUU-13 has 40 downward firing ejection tubes in its central section. Each ejection tube has an inside diameter of approximately 4.7 inches and is about 11 inches long. The SUU-13 was used to dispense several different submunitions and was therefore a component of several different CBUs.

The BLU-19 submunition is a steel cylinder 4.6 inches in diameter and approximately 9.4 inches in height. It contained approximately 4 pounds of Sarin and a high explosive burster along its central axis. The BLU-19 was used only with the SUU-13 dispenser and is associated only with the CBU-15 designation.

In the CBU-15 configuration, a single BLU-19 is loaded in each of the SUU-13 ejection tubes. When initiated by the pilot, the BLU-19s are ejected downward at a preset time interval. The BLU-19s will impact the ground in a long line with the length of the impact line dictated by the time interval between ejection's and the speed of the aircraft. Prior to initiating the ejection sequence, the pilot would be expected to position his aircraft such that the line of submunition impacts would occur upwind of the intended target and perpendicular to the wind direction. Prevailing winds would then, hopefully, cause the cloud of agent to drift across the target.

The use of CBU-15 munitions as reported is highly unlikely for several reasons including the following.

  • Use of the CBU-15 would have violated the presidential order.
  • BLU-19 submunitions, a component of the CBU-15, were not available in South Vietnam.
  • The report stated that the U.S. forces were equipped with the M-17 mask. The mask, alone, is insufficient protection from the effects of Sarin. In addition to the respiratory and ocular routes of exposure, Sarin is also effective, though less so, via skin absorption. Members of the U.S. force were reported to have rolled down their uniform sleeves to protect them for the effects of the chemical agent on their skin. Rolling down the sleeves of the typical uniform of that period would not have provided significant protection from Sarin.
  • The probable effects of Sarin on unprotected exposed personnel are inconsistent with the effects described in the report. Though reportedly exposed to aerosolized agent and lacking protective equipment appropriate for Sarin, no one in the U.S. force is reported to have developed symptoms typically associated with moderate to severe Sarin intoxication. Some of the symptoms of mild exposure to Sarin via inhalation are similar to the symptoms of exposure to CS. Additionally, miosis is typical following inhalation of minimal quantities Sarin vapor but would not be expected following the inhalation of CS. Miosis was not a reported symptom.

If U.S. Air Force aircraft dropped a chemical munition it was probably the CBU-30. The CBU-30 consisted of the SUU-13 dispenser and 40 CS filled CDU-12 subclusters. CS is a riot control agent that is not typically lethal in field concentrations.

The CDU-12 subcluster is dimensionally similar to the BLU-19. The CDU-12 contains 32 BLU-39 CS filled submunitions. Following ejection from the SUU-13, the CDU-12 first ignites the BLU-39 submunitions then ruptures in air, releasing the BLU-39 submunitions.

The BLU-39 submunition is approximately the size of a D-cell flash light battery and contains a CS/pyrotechnic mix. Following ignition of the CS/pyrotechnic mix and release from the CDU-12 subcluster, the BLU-39s impact the ground and "skitter" due to the escaping stream of hot CS and pyrotechnic gases. The skittering action further scatters the BLU-39 submunitions across the target area.

The use of CBU-30 munitions is probable for several reasons including the following.

  • Use of the CBU-30 would not have violated the presidential order.
  • The CDU-12s filled with BLU-39 submunitions were available and in use in South Vietnam.
  • The M-17 mask, alone, is sufficient protection from the respiratory and ocular effects of CS. Rolling down the sleeves of the uniform shirt would provide some protection from the skin irritation caused by exposure to CS. Personnel who had either lost their mask or who had a defective or poorly fitted mask would be incapacitated to some extent but they would not be expected to succumb to the effects of CS intoxication.
  • The probable effects of CS on unprotected exposed personnel are consistent with the effects described in the report.

Department of the Army Field Manual FM 3-2, TACTICAL EMPLOYMENT OF RIOT CONTROL AGENT CS, dated 8 April 1970 includes, on page 3-4, a table entitled "figure 3-1. CS munitions for principal tactical application." Under the heading "Air Delivered," seven munitions are listed including the CBU-15. Of these, four are identified as suitable to either "Rout enemy from fortified positions" or to "Suppress enemy fire." Only two, the CBU-19 and the CBU-30 are U.S. Air Force munitions. The CBU-19 is described, on page 4-8, as being "… obsolete and no longer in production" and "… rarely used…" The only CBU containing CS likely to be available and appropriate for the mission described in the report was the CBU-30.

Based on the foregoing analysis we conclude that U.S. forces supporting OPERATION TAILWIND did not use lethal nerve agents.

Related Links

Mustard: An Ambiguous Term
Harvey J. McGeorge
Public Safety Group
May 28, 1998

In 1822 Despretz reacted ethylene with sulfur chloride to yield bis(2-chloroethyl) sulfide more commonly known as sulfur mustard or mustard gas. Over the next 100 years at least six other reactions for the production of mustard were devised. Each yielded sulfur mustard but differed in the immediate precursors, the purity of the mustard produced and the specific byproducts. These initial production routes include the following.

  1. Ethylene reacted with sulfur chloride - Despretz, 1822
  2. Chlorine reacted with ethyl sulfide - Richie, 1854
  3. Thiodiglycol reacted with phosphorus trichloride - Meyer, 1886
  4. Thiodiglycol reacted with hydrochloric acid - Clarke, 1912
  5. Ethylene (dry) reacted with sulfur dichloride - Gibson and Pope, 1920
  6. Thiodiglycol in chloroform reacted with thionyl chloride in chloroform - Steinkopt, 1920
  7. Sulfur dichloride(75) and sulfur monochloride(25) reacted with ethylene - Meyers and Stephen, 1920

Various procedures for improving the purity of sulfur mustard were devised including the following.

  1. Vacuum distillation - HD United States
  2. DESA process - South Africa

During the period 1918 to 1945 over 200,000 tons of "mustard" was produced by at least 10 countries including the following.

Canada Japan
France Poland
Germany United Kingdom
Hungary United States
Italy USSR
South Africa  

Since WWII at least another six countries are known to have produced mustard in one form or another.

A cursory review of this production reveals that, in addition to sulfur mustard, at least six other primary compounds were produced. These primary compounds included the following.

  1. Bis(2-cholorethyl)sulfide - basic sulfur mustard
  2. 1,2-bis(2-chloroethylthio)ethene - sesqui mustard
  3. Bis(2-chloroethylthioethyl)ether - oxygen mustard
  4. Sulfur mustard with a methyl group- Ziakov mustard
  5. Bis(2-chloroethyl)ethylamine - nitrogen mustard 1
  6. Methyl-bis-(2-chloroethyl)amine - nitrogen mustard 2
  7. Tris(2-chloroethyl)amine - nitrogen mustard 3

In addition to being used singly as munitions fillings some of these compounds were mixed with sulfur mustard to lower its freezing point. Examples include the following.

  1. Sulfur mustard mixed with sesqui mustard - HQ United States
  2. Sulfur mustard mixed with oxygen mustard - HT United States

Sulfur mustard was also mixed with other chemical agents or compounds to either reduce its freezing point or to achieve some other desired effect. Examples include the following.

  1. Sulfur mustard with lewisite - HL United States, RK-7 USSR
  2. Zaikov mustard with dichloroethane - USSR
  3. Sulfur mustard with thickeners - HVV United States
  4. Zaikov mustard with thickeners - VIR-16 USSR

Yet further combinations were created when stabilizers were added to retard decomposition in storage. At least some of these combinations were apparently identified by a unique code painted on the munition. The following stabilizers are known to have been used with mustards.

  1. Carbon tetrachloride - France and Germany
  2. Chlorobenzene - France and Germany
  3. Chloropicrin - United States
  4. Nitrobenzene - Germany
  5. Aeridine - K USSR
  6. Beta-naphthoquinoline - N USSR

In summary there are dozens of unique compounds and mixtures loaded in munitions or other containers that are all loosely referred to as "mustard gas." This broad generalization leads to confusion and mistakes on the part of investigators and analysts.

Vaccinations Against Anthrax for U.S. Forces


In November of 1997, Secretary of Defense Cohen announced a six year, $130 million plan to vaccinate all 2.5 million U.S regular and reserve forces against Anthrax. In early March, at the request of General Anthony Zinni, the Pentagon announced plans to accelerate the time table for initiation of the actual vaccinations. Troops in the Persian Gulf will, this week, begin receiving the first of six vaccinations over an 18 month span.

The sole U.S. Producer of Anthrax vaccine is Michigan Biological Products Institute (MBPI), which is operated by the Michigan Department of Public Health. The vaccine has been licensed in the U.S. since 1971. The usually authoritative ASA Newsletter reports in its 12 February 1998 issue that MBPI is up for sale and had been scheduled to close in February. BG John Doesburg reportedly said that the Pentagon cannot operate the facility (27 buildings and 153 workers).

PSG Commentary:

The effectiveness of the vaccine against the pulmonary form of Anthrax has been questioned. Data from the highly regarded U.S. Army Medical Research Institute of Infectious Disease (USAMRIID) at Ft. Detrick states that, "two doses of vaccine protects against 200-500 LD50's in monkeys." This means that two doses of the vaccine, given two weeks apart, provided a high degree of protection (animals didn't get sick) when the test animals were exposed to inhalation doses of Anthrax spores 200-500 times the amount typically needed to initiate a lethal infection in 50% of the exposed monkeys. The estimated LD50 for unvaccinated humans is 8-10,000 spores. Assuming that the degree of protection afforded humans was similar to that found in monkeys, the dose needed to cause an infection in 50% of the vaccinated personnel raises to between 1.6 and 5 million spores. This may seem like a large number but it is achievable, particularly in circumstances where there is no warning and especially in a confined space such as a building.

The effectiveness of the vaccine against the various strains (varieties) of Bacillus Anthracis (the bacteria which causes Anthrax) is another cause for concern. Recent studies have shown that multiple strains of B. Anthracis were present following the 1979 incident in the Russian city of Sverdlosvsk. This suggests, but does not prove, that the former Soviet Union was, at least, experimenting with a mixed strain Anthrax agent. Further, it is unknown if this mixed strain technology, if it actually exists, has been transferred to either Iraq or one of the other states with an active BW program. The effectiveness of the current vaccine against a mixed strain agent is presumed to be high but needs to be validated. A potentially more effective Anthrax vaccine is under development at USAMRIID.

The following points are important to remember when considering vaccines and biological warfare or terrorism.

  • Vaccines are an important part of the defense against biological warfare agents.
  • Vaccines alone will not reliably protect you from the deliberate use of a biological warfare agent.
  • Vaccines are best used as a pre-treatment in conjunction with respiratory protection and, when necessary, post exposure treatment with antibiotics or other therapy.



  Graham, Bradley. All-Force Inoculation Timetable Moved Up. The Washington Post, 4 March 1998.
  Price, Barbara. And on Anthrax Vaccines. Bioscope '98. The ASA Newsletter, Issue Number 64, 12 February 1998.
  Price, Richard ed. U.S. Vaccine Lab for Sale. On the Street, The ASA Newsletter, Issue Number 61, 23 August 1997.
  Medical Management of Biological Casualties Handbook, Second Edition. USAMRIID, Ft. Detrick, Frederick, Maryland. August 1996.

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