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Riot Control Agents (RCA)

Riot Control Agents (RCA) disable hostile forces or rioting personnel for limited periods of time by producing temporary disabling physiological effects when they come into contact with the eyes or skin or when they are inhaled. Their effects are typically peripheral, such as irritation to the eyes, mucosa, respiratory tract, or skin. The effects generally subside quickly once the individual is removed from the atmosphere of the RCA.

On the other hand, incapacitating concentrations can act systemically, have longer lasting, more profound physiological effects such as immobilization of limbs, systemic interference of breathing, disruption of cognitive function or any of several other centrally controlled effects. The physiological effects may continue after personnel leave the target area. RCA levels at 5-10 milligrams per cubic meter (mg/m3) achieve incapacitating concentrations. Training concentrations (1-3 mg/m3) for CS are irritating concentrations normally found in chamber or field training exercise settings. In tactical concentrations, RCAs do not permanently injure personnel but should be used like incapacitating agents. In enclosed places, prolonged exposure to the resulting high dosages of RCAs can kill or disable personnel and can cause serious physiological reactions.

RCAs and their use date back to the development of organized chemical warfare during the First World War. RCAs were available to US forces in every major conflict thereafter. The US military made great use of RCAs during the conflict in Southeast Asia. This usage proved to be controversial and also led to allegation of use of other chemical weapons, which remained at issue well after the conflict had ended. Most notably, on 7 June 1998, the Cable News Network (CNN), in coordintation with Time magazine, ran a story alleging that a US Special Forces unit was inserted into Laos in September 1970 to kill US military defectors. The telecast further alleged that US Air Force A-1 Skyraider aircraft had dropped Sarin nerve gas CBU-15/B cluster munitions on the enemy base camp prior to the attack by the Special Forces unit. The next day, Time magazine, dated 15 June 1998, included a similar story on Operation Tailwing, written by CNN staff. A subsequent investigation by the US Air Force concluded that on 13 and 14 September 1970, A-1s from the 56th Special Operations Wing had in fact dropped CBU-30/B CS tear gas cluster munitions to assist in the extraction of the Special Forces unit, which had been inserted to conduct operations against the Ho Chi Minh Trail. In 1968, then Secretary of Defense Robert McNamara had authorized the use of RCAs for such purposes.

It remained the position of the United States that the use of chemical munitions for any military purpose of the United States that was not connected with the use of a chemical weapon and that was not dependent on the use of the toxic or poisonous properties of the chemical weapon to cause death or other harm was not prohibited under the international Chemical Warfare Convention. Similarly, the use of chemical munitions for any law enforcement purpose, including any domestic riot control purpose and including imposition of capital punishment was also not understood to be prohibited.

However, in 1971, President Nixon renounced the "offensive" use of incapacitating agents such as BZ in war. Then in 1975, President Ford renounced renounced the first use of RCAs in war in all situations except in defensive military modes to save lives. These situations included: Use of riot control agents in riot control situations in areas under direct and distinct U.S. military control, to include controlling rioting prisoners of war; use of riot control agents in situations in which civilians are used to mask or screen attacks and civilian casualties can be reduced or avoided; use of riot control agents in rescue missions in remotely isolated areas, of downed aircrews and passengers, and escaping prisoners; and use of riot control agents in rear echelon areas outside the zone of immediate combat to protect convoys from civil disturbances, terrorists and paramilitary organizations. The Secretary of Defense was to take all necessary measures to ensure that the use by the Armed Forces of the United States of any riot control agents and chemical herbicides in war was prohibited unless such use has Presidential approval, in advance. The Secretary of Defense would prescribe the rules and regulations he deems necessary to ensure that the national policy herein announced shall be observed by the Armed Forces of the United States.

RCAs could still be used on US bases, posts, embassy grounds, and installations for protection and security purposes, riot control, installation security, and evacuation of US noncombatants and foreign nationals and off-base worldwide for the protection or recovery of nuclear weapons under the same conditions as those authorized for the use of lethal force. Only the Secretary of Defensec could the use in the latter situation. RCAs also remained in use during training in the United States and where authorized abroad.

RCAs produce effects that must be considered for both tactical and training uses. The RCAs in training concentrations will produce temporary, irritating effects to normal, healthy individuals. These personnel will recover from the exposure quite rapidly. However, individuals with a common cold, asthma, lung congestion, high blood pressure, or cardiovascular problems will experience increased effects and may suffer longer recovery times. Therefore, they should not be exposed to these agents during training exercises. Pregnant soldiers with an exempt letter from a doctor should also be exempt from training with RCAs.

Particles of CS remaining on exposed skin for long periods can cause severe burns. CS should be immediately flushed from the skin with cold water.

Prolonged, continuous, or even intermittent exposure to field concentrations of CS combined with a high temperature and humidity may result in a cumulative effect (more intense stinging, tearing, watering of the eyes).

Food and drink contaminated with CS can be detected easily since it is quite repulsive to the taste. When food items are suspected to have been contaminated by CS in training, check them using the following procedures: (Do not use these procedures in combat when chemical or biological agents may also be present.)

  • If packaged, clean the package and check for leaks or damage. If no odor is present, the food is probably not contaminated. If the package is damaged or leaking, unpack the contents and inspect them.
  • If unpacked, sniff to detect RCA odor. If none the food may be safe to eat. However, when in doubt, discard the package. If the food is contaminated, you may be able to trim the food and remove the contaminated portions. The same procedures apply to food immersed in water or in covered containers. CR should be stored in nonporous containers on nonporous surfaces. It will leach into porous material and can be extremely persistent.

The behavior and tactical effectiveness of RCAs in support of military operations are affected by the weather, by the terrain in the target area, and by the defense posture and training of target population. Understanding weather effects on RCA agent behavior is essential to ensure maximum effectiveness in planning and conducting operations.

Conditions that are most favorable for RCA dispersion and placement on a target would be stable (inversion) atmospheric conditions where the wind speed is less than 5 to 8 knots. Under neutral atmospheric conditions with low windspeed and smooth terrain, large areas may be covered with RCAs. Neutral conditions may be the best for military planning purposes since these conditions usually occur more often than stable or unstable conditions. The least favorable conditions for RCA employment are heavy rains and unstable (lapse) atmospheric conditions where windspeeds are greater than 10 knots. Although light rains will not seriously degrade the effectiveness of most RCAs, heavy rains will wash RCAs out of the air and off surfaces.

Temperature also has an effect on RCAs. Although the rate of evaporation of liquid RCAs increases with increasing temperatures, humans perspire more freely at higher temperatures, increasing skin effects from RCA exposure. In contrast, at lower temperatures, personnel will be wearing multi-layered clothing that provides a more effective barrier to skin exposure. In this case, RCAs may still be employed effectively for delayed harassing effects against troops who must eventually remove their contaminated clothing.

Terrain, contour, and surface areas also influence the effectiveness of RCAs. Under stable weather conditions, the agent cloud tends to flow over rolling terrain and down valleys. Higher concentrations tend to flow around obstacles such as hills and persist in hollows, low ground, depressions, and foxholes. In urban areas, the dominating terrain (buildings, streets, and trees) tends to channel wind and create eddies and currents that can be very unpredictable and cause the agent cloud to dissipate more rapidly. Turbulence on the downwind sides of buildings will tend to pool RCA concentration close to the buildings, and may penetrate closed structures through doors and windows.

Rough ground and ground covered with tall grass or brush tends to deflect and retard cloud movement, while flat terrain and open water (under stable or neutral conditions) allows an even, steady cloud movement and flow.

When RCAs are employed into wooded areas, the thickness and height of foliage determines agent effectiveness. A dense canopy tends to create a physical barrier that resists penetration of aerosol and particulate clouds from the outside while preventing escape of RCAs already under the canopy. The agent clouds released from munitions within woods and jungles are generally smaller and higher in concentration (by as much as three times) than those released in the open. Wooded and jungle environments also require larger munition expenditures because some rounds will detonate on treetops with less agent penetrating to ground level.

Soil type and condition also affect the efficiency of RCA munitions. For instance, point detonating devices tend to bury into the porous surfaces and evaporate more slowly than from nonporous surfaces. As a result, a decrease in the cloud size and area coverage could occur. When this soil is disturbed by traffic, the RCAs may become airborne with renewed effectiveness.

The overall utility of RCAs is greatly influenced by the discipline, motivation, and degree of readiness of the soldier. RCAs have been shown to be least useful against well-trained and well-equipped soldiers. Test results have shown that a very high level of adaptation or tolerance to CS may develop under conditions of extreme motivation or where escape to clean air is not possible. However, RCAs in surprise dosages can still incapacitate significant numbers of well-trained and equipped soldiers. Performance degradation will be achieved when enemy soldiers are forced to don protective clothing and masks. Enemy use of terrain may also be restricted. RCAs can also be used to complement or enhance other munitions beyond the effectiveness or either used alone.

In many tactical situations, the employment of RCAs cannot wait for optimum environmental conditions. Their effectiveness often depends on immediate use when and where the situation demands. When employed under adverse conditions, additional munition expenditures and off-target attacks may increase on-target RCA effects. However, RCA employment depends primarily on the tactical situation, regardless of the conditions that exist at the time.

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Page last modified: 16-01-2013 16:54:43 ZULU