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The primary purpose of using NBC weapons and smoke is to produce casualties, destroy or disable equipment, and generally disrupt operations. NBC weapons and smoke are employed in coordination with conventional weapons. FM 3-3, FM 3-4, FM 3-5, and FM 3-50 describe NBC defense and smoke operations. This appendix addresses the effects of a desert environment on NBC weapons.


Both desert weather and terrain affect the behavior of NBC and smoke weapons, and to some extent influence their tactical employment. The following paragraphs describe the effects of the weather and the terrain on the behavior of NBC weapons.


The effectiveness of NBC and smoke weapons is directly proportional to air stability. Air stability is a result of temperature variations at different levels of the air. The span of desert day and night temperatures causes extremes of air stability. At night and early morning the desert air is very stable. This may be the best time for NBC and smoke employment because of extensive downwind drift and area coverage. Desert air is very unstable during the late morning through afternoon. This may be the worst time for NBC and smoke employment because of quick and irregular dissipation. This may lead to ineffective target area coverage and possible danger to friendly troops. Temperature differences are determined by comparing the air temperature differences every 3.5 meters above the ground. Three types of temperature differences influence NBC and smoke operations:

  • Unstable (lapse). Unstable conditions exist when air temperature decreases with altitude. In the desert, this mostly occurs between late morning and early evening.

  • Neutral. Neutral conditions exist when air temperature does not change with altitude, In the desert, this mostly occurs during early morning and early evening.

  • Stable (inversion). Stable (inversion) weather conditions exist when the air temperature increases with altitude. In the desert, this mostly occurs between late evening and early morning.

High desert temperatures in the middle of the day result in a decrease in air density, so nuclear blast waves move faster. Some chemical agents that come in contact with the skin are more effective during high temperatures due to perspiration. Desert sunlight is lethal to the effectiveness of most biological agents, but most are unaffected at night.

High winds are common in certain desert seasons and affect the dissemination of biological, chemical, smoke, and radioactive clouds. High winds may break up clouds in an odd fashion and force them in the wrong direction and possibly endanger friend] y troops.


Flat desert terrain lacking vegetation and under stable air conditions moves NBC and smoke effects evenly and steadily in all directions. Nuclear induced radiation is greater in sandy soil due to the high silica content. Desert soil below the surface crust is a fine powder, so the blast and suction effects of a nuclear burst will cause considerable dust clouds.


Many potential threat nations maintain nuclear weapons and additional nations continue to obtain nuclear capability. Nuclear weapons can be delivered by missiles or bombs and can be exploded in the air, on the ground, or below the ground. Depending upon the radiation dosage received, lethal effects could be felt immediately or delayed for days. Detonated nuclear weapons release energy that affects military troops and equipment in three forms: blast, nuclear radiation, and thermal radiation (heat and light). These effects are discussed in the following paragraphs.


Nuclear blasts, even from an air burst, raise considerable amounts of desert sand and dirt, which inhibits observation and maneuver for a long time. Lighter desert air density causes a drop in static overpressure, but a more rapidly expanding blast (shock) front. This increases the danger to aircraft and helicopters flying in the area. The radius of damage is normally smaller in desert climates so dug-in personnel and equipment are safer. Desert trafficability is degraded in the immediate area of the strike, especially for wheeled vehicles, due to the destruction of the sand crust.

Nuclear Radiation

Immediate nuclear radiation is a function of weapon yield and changes little with desert temperature. Residual radiation is high in the case of low air burst or ground burst weapons. Residual radiation in the desert is affected by the time of day and the wind. At night, with no wind, residual radiation may be evenly distributed around the point of burst. At night, with a steady wind, residual radiation may drift downwind for many miles. In the late afternoon, residual radiation may drift in a totally irregular pattern and direction due to desert air instability. Induced radiation is prevalent in desert sand due to the amount of silica in the soil. Constant radiation monitoring and reconnaissance are vital to protect troops, especially from contaminated water sources.

Thermal Radiation

The effective range of thermal radiation (heat and light) increases in the desert where there is little terrain masking. This increases the danger of troops receiving severe burns. Blinding light (dazzle), out to 50 kilometers, must be considered in the desert when determining the radius of warning for friendly troops.


The United States has renounced the use of biological agents, but many potential threat nations maintain biological weapons. Biological agents are living microorganisms that multiply inside the human body and cause disease. Biological agents may be disseminated as a liquid or vapor using rockets, bombs, or aerosol generators.

Depending upon the agent, they can produce lethal effects in 1-24 days from the time of exposure. High desert temperatures (120 degrees Fahrenheit and higher) and sunlight may destroy most biological agents. Cooler nighttime temperatures and the lack of sunlight provide biological agents a chance to enter the body. High desert winds will disperse biological agents more rapidly than low winds. Normally, the most effective wind speeds for effective target coverage are from 8-18 knots (14-32 kmph). Stable desert air conditions (night or early morning) provide the greatest agent concentration and area coverage. Unstable desert air conditions (late morning and afternoon) promote atmospheric mixing and lower agent concentration, reducing effective target coverage.

Biological weapons are best suited for strategic rather than tactical use in the desert. Test water and food sources frequently to ensure they are not contaminated. Sanitation, personal hygiene, and immunizations must be instituted to ensure individual protection.

The United States also renounces the use of toxins but some potential threat countries continue to develop toxins for possible military use. Toxins are extracted from natural biological sources and are not chemicalIy produced. They can be disseminated as a liquid, vapor, or powder, and delivered by aerosol generators, artillery, rockets, or bombs. Depending upon the toxin, they can produce lethal effects in one minute to 12 hours from the time of exposure. In the desert, toxins can effectively be used as strategic or tactical weapons.


The United States has reserved the right to retaliate in kind with chemical agents against enemies who use them frost. There are six major types of chemical agents: nerve, blood, blister, choking, incapacitating, and tear. They are classified as persistent and nonpersistent. Chemical agents may be delivered by mines, rockets, artillery, or bombs. Depending upon the agent type, lethalities can occur between minutes to an hour from the time of attack.

High daytime temperatures of the desert increase incapacitating effects of liquid agents, which rely on skin penetration. Desert air instability (late morning and early afternoon) will usually cause quick, vertical and irregular dissipation of chemical agents. This reduces the lethal concentration and target area coverage. Desert air stability (early morning and evening) will most likely cause adequate agent dissipation and target area coverage. High desert temperatures also cause liquid agents to evaporate more quickly and decrease the time of hazard. If a liquid chemical agent soaks into the desert sand, it will increase the time of hazard. Figures D-1 and D-2 show the evaporation times of chemical agents (HD, GA, GF, VX) on sand at 104 and 68 degrees Fahrenheit for negligible risk levels. Negligible risk levels cause mild incapacitation among no more than 5 percent of unprotected soldiers/marines crossing a contaminated area.

Strong desert winds also increase the evaporation rate of liquid agents. They cause chemical clouds to drift downwind in an irregular direction and concentration. This tends to disperse target area coverage and lethal concentrations, and may endanger friendly troops.


The lack of cover and concealment in flat desert terrain with little vegetation makes the use of smoke more vital to survival.

Desert winds, temperature, humidity, and terrain all affect smoke cloud behavior. The weather condition with the greatest impact on smoke operations is wind. Low desert winds al1ow smoke to remain on target areas for a longer period of time than high winds, In general, if the wind speed is less than 5 knots (9 kmph) or greater than 10 knots (18 kmph), smoke may not provide good target area coverage.


Desert temperature differences have a direct relationship with making effective smoke. Three types of temperature differences influence smoke:

  • Unstable (lapse). Lapse desert temperatures tend to break up and dissipate smoke, but are best for producing smoke curtains.

  • Neutral. Neutral desert temperatures have limited vertical air currents and are good, but not the best, for producing smoke hazes and blankets.

  • Stable. Stable (inversion) desert temperatures have no vertical air currents, and are the best for producing smoke hazes and blankets.


Practically all smoke particles absorb moisture from the air. The lack of moisture in the desert air decreases the particle size and density of smoke making it less effective. Desert smoke streamers are shorter and less dense than smoke streamers in humid weather conditions. This increases the time and distance required to build adequate target area coverage.


The effects of NBC weapons and smoke on tactics in desert operations are discussed in the following paragraphs.


Nuclear weapons have a major bearing on tactics because of their ability to contaminate and shape desert terrain by making it impassable. Nuclear weapons can destroy troop and equipment concentrations and command and control centers and are usually considered weapons of mass destruction and combat multipliers; therefore, a smaller force with nuclear weapons may well defeat a much larger force without nuclear weapons.

The high maneuverability of tracked vehicles in the desert produces an endless number of avenues of approach. This creates difficulties for defense operations in the desert. Nuclear explosions could be used to shape desert terrain and canalize an enemy. This would provide profitable targets for other weapon systems. Equally, an attacking force could employ nuclear weapons in the desert to cut off enemy reinforcements, isolating them and making them vulnerable.

Biological Agents/Toxins

High desert temperatures and sunlight prevent the effective use of most biological agents during the daytime. An exception is spore-forming (anthrax) biological agents. During the day, troops crossing or occupying desert terrain face little danger from long-term biological contamination (except from spore-forming agents). But, because of favorable night desert conditions, an aerosol-delivered attack or a liquid biological attack would be effective. During night desert conditions, biological agents could effectively cover hundreds of square kilometers with a small amount of agent. This type of attack could be conducted covertly. These agents could contaminate vast areas of terrain and create mass casualties.

Toxins in the desert have nearly the same military use as chemical agents and are employed in the same manner. However, toxins are more deadly and require lower concentrations for lethalities. Toxins are difficult to detect with today's standard detection equipment.

Chemical Agents

The versatility of chemical agents gives commanders flexibility in desert operations. Commanders must consider how the employment of chemical agents affect offensive and defensive desert operations. Chemical agents can be used to create casualties, degrade performance, slow maneuver, restrict terrain, and disrupt logistical support. An assaulting force could use chemical agents to breach a defense or widen a gap. The best agent to use in this case would be a nonpersistent agent (one that is fast acting and leaves the target area quickly). High explosives could be mixed with the chemical attack to conceal the use of chemicals and complement their effects.

The threat of a chemical attack forces the use of protective masks and clothing. Heat, fatigue, and stress seriously affect the performance of troops. This is especially true with high desert temperatures. Well-trained soldiers/marines tolerate wearing protective gear better than those who are not as well trained. Troops in protective gear fire weapons less accurately, move more slowly, and must rest more often.

The actual or anticipated use of chemical weapons slows down a force and forces troops to take precautions. Desert heat, fatigue, and stress caused by wearing protective equipment slows down unit movement. Chemical agents can be used to create contaminated obstacles to desert maneuver. The best agent to use in this case would be a persistent chemical agent (one that remains on the target area for a time).

Chemical agents could be used to support offensive desert operations. Chemical agents could be used to protect flanks along an axis of advance to slow enemy counterattacks and to slow enemy fire and movement. In defensive desert operations, chemical agents could be used against second echelon forces to separate, slow down, and isolate them.

Chemical agents could be used to supplement conventional obstacles, or they could be used alone to restrict desert terrain. They may slow maneuver and channel attackers into engagement areas. A commander could contaminate a narrow desert mountain pass or bridge with a chemical agent and force the enemy to use an alternate route.

Logistical centers are lucrative targets for desert chemical attacks. Contaminating logistical supplies and equipment reduces the mobility of reinforcements and slows the delivery of supplies and equipment.


Smoke is a combat multiplier that enhances the commander's ability to concentrate combat power at the critical time and place. Smoke is a far more significant battlefield factor than ever on flat desert terrain with little cover and concealment. Smoke can defeat enemy binoculars, weapon sites, and laser range finders in the desert. Smoke placed on the enemy at night interferes with enemy operations and observation by defeating enemy night sights and infrared sights.

In the desert offense, smoke can be used to deny the enemy information about the size, composition, and location of friendly maneuver forces. A smoke screen can be placed either to the front or to the flank. When the enemy cannot be screened effectively, obscuring smoke may be required. We must keep the enemy in doubt about the attacking unit's strength, position, activities, and movement. The longer the enemy is in doubt during an operation, the greater the chances are for mission success. Also, smoke can conceal desert breaching operations and river or gap crossings. It can also be used in deception operations.

In the desert defense, smoke is used to deny the enemy information about the size, location, and composition of friendly defensive positions. We must deny the enemy information by concealing the preparation and location of battle positions, artillery units, and reserves. Smoke can be used to support desert defensive positions by slowing enemy maneuver, disrupting command and control, isolating attacking echelons, silhouetting targets, and concealing obstacles.


The commander of troops in desert operations must choose between the two following options when there is the threat of NBC warfare:

  • Troops remain unprotected, with a high-chemical casualty risk, but a lower chance of heat fatigue.

  • Troops are fully or partially protected, with a low-chemical casualty risk, but a higher chance of heat fatigue.

A decision on the level of protection is made according to the circumstances. If partial protection is ordered, the pace of physical work will be slower and proficiency reduced. The bulk of strenuous physical activity must be done at night or during the coolest part of the desert day.

In the desert, heat casualties (5 percent minimal) can be expected to occur in 30 minutes while performing heavy work in 90-degree-Fahrenheit temperatures when dressed in MOPP 4. Work/rest periods must be utilized to reduce the chances of heat fatigue. When protective clothing is worn, at least 10 degrees should be added to the WBGT index. Because of higher body temperatures, soldiers/marines in MOPP equipment perspire more than usual. Water must be consumed (2 quarts per hour) during continuous moderate work periods (and in MOPP equipment) when temperatures reach 80 degrees Fahrenheit and above to replace lost fluids or dehydration will follow.


The main problem of decontamination in the desert is lack of water, Although decontamination takes place as far forward as possible, the lack of water may burden the logistical system. Weathering may be a viable option for chemical contamination. The persistency of nerve agents (GA, GF, VX, GD) and mustard (HD) on chemical agent resistant coating (CARC) painted vehicles is between 4-24 hours at 104 degrees Fahrenheit. Sea water may be used as a substitute for fresh water during normal decontamination operations, but all equipment must eventually be flushed with fresh water to prevent corrosion.

Desert sand can be used for chemical decontamination, but it increases soldier/marine fatigue during its application. Sand removes most, but not all, liquid contamination, and saves valuable water supplies; however, the absorption capacity of desert sand is exhausted in 30-60 seconds after application. Remove the sand by sweeping or brushing the contaminated surface. Chemical agent detection should be conducted to ensure the agent is adequately removed.

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