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The Threat of Chemical and Biological Weapons

When the wind shifted on the afternoon of April 22, 1915, on fields near Ypres, France, the Imperial German Army ushered in a new age of warfare.

World War I (1914-1918) had become a brutal standoff of opposing infantries fighting from fortified trenches. To break the stalemate, the German Supreme Command made a fateful decision to change strategy. At 5 p.m. German combat engineers opened 5730 cylinders of compressed chlorine gas. Blown by the wind, this vast yellowish-green cloud wafted across the battlefield toward the unprepared Allied lines.

Suddenly enveloped and choking from the mysterious gas, French and Belgian troops in the trenches turned and ran for their lives. Unopposed, but wary of the ominous cloud, the German infantry advanced a few hundred meters toward Allied lines and then dug in for the night.

The full price of developments in modern science began coming into view on this day. The science of chemistry had progressed steadily in the late 1800s and early 1900s, but it was on this day, in the blood-soaked fields of France, that newly isolated chemical agents (chemicals in a concentrated form) were first used for destructive purposes. The chemical weapons used in World War I were the first true “weapons of mass destruction.” Biological weapons of mass destruction would emerge in the 1930s, followed by nuclear weapons in the 1940s.

As chemical, biological, and nuclear weapons proliferated around the world and the technologies behind them advanced, they would together emerge as one of the most serious threats to human existence and international security ever produced by human beings. Scientific progress could bring knowledge and prosperity, but it could also provide new, ever-better tools for killing people or rendering lands uninhabitable.

During the Cold War, international attention focused primarily on nuclear weapons, which the United States and the former Union of Soviet Socialist Republics (USSR) produced and deployed in numbers sufficient to destroy the world many times over. Chemical and biological weapons (CBW) were regarded as second-tier weapons, in part because military experts assumed that their use would lead quickly to a nuclear exchange. Thus, despite building vast arsenals of chemical and biological weapons, neither weapon type was taken very seriously by the United States or the USSR during the Cold War.

Attitudes toward chemical and biological weapons began to change with the passing of the Cold War and the dissolution of the USSR in 1991, particularly among U.S. military officials and experts. The Persian Gulf War (1990-1991) was in many respects a wake-up call for the U.S. military, which realized early in the conflict that it was not well prepared to cope with the CBW threat posed by Iraq. Many military strategists now regard chemical and biological weapons as one of the foremost threats to U.S. national security interests.

Some experts have argued that chemical and biological weapons are now more likely to be used than nuclear weapons, whether by an aggressive state, such as Iraq, or by a terrorist group, such as the Japanese cult Aum Shinrikyo, which attacked the Tokyo, Japan, subway with nerve gas in March 1995. United States security officials and experts are now beginning to focus on the contemporary CBW threat. They are trying to understand how scientific developments are changing this threat and working to better prepare the nation for future CBW incidents.

Chemical and Biological Weapons: An Overview

Technologically, chemical and biological weapons are almost entirely different. Chemical weapons are highly toxic, manufactured substances that can be disseminated as vapors, aerosols, or liquids. Biological weapons, on the other hand, are living, disease-causing microorganisms or toxins (deadly chemicals derived from living organisms) which, in their most effective form, are disseminated as aerosols that are inhaled.

There are four basic types of chemical warfare agents. Choking agents, such as chlorine and phosgene, attack the victim's lungs through inhalation and produce death or incapacitation by interfering with breathing. Blister agents, such as mustard gas and lewisite, destroy human skin and tissue through both inhalation and direct contact with the skin. Blood agents, such as hydrogen cyanide, block the transfer of oxygen through the blood system, and cause injury or death from anoxia (a deficiency of oxygen reaching bodily tissues).

The most lethal chemical warfare agents are nerve agents, such as sarin, tabun, and VX, which produce convulsions and death by blocking an enzyme (acetylcholinesterase) needed to transmit messages in the nervous system. Nerve agents can be lethal in minute amounts: A tiny drop of VX on the skin, for example, can overcome an adult human in a matter of minutes.

Chemical weapons require a dissemination system, such as a sprayer or explosive device. Once released against an unprotected population, chemical weapons tend to function quickly and can produce noticeable symptoms within an affected group in a matter of seconds or minutes. Most chemical weapons have a distinctive odor and can be seen in the atmosphere. Exposure to a chemical warfare agent is not necessarily fatal, since the effects of chemical weapons depend on a wide range of factors, including dose, the length of time a person is exposed, the level of protection a person has, and whether medical treatment is available. The effects of chemical weapons are also highly dependent on terrain and weather.

Chemical weapons can be extremely effective against civilians and unprepared military forces, although literally tons of agent are needed to create lethal doses in large open areas. Properly prepared military forces, on the other hand, should be able to withstand an enemy's chemical attacks if they possess adequate chemical warfare training and equipment, such as gas masks and protective clothing. Chemical defenses do, however, impose additional physical and logistical demands on military operations.

Biological weapons (excluding toxins, which resemble chemical weapons) consist of living, infectious microorganisms that are disseminated as aerosols through the atmosphere. Inhaled into the lungs, biological agents begin to multiply within the body, causing a disease that can incapacitate or kill the victim. Biological warfare aerosols are generally invisible, odorless, and tasteless. The onset of symptoms is usually delayed, often for as much as three to five days, so the victim of biological warfare may not even know that an attack has occurred until the disease has reached an advanced stage.

In principle, any disease-causing organism—bacteria, viruses, parasites, even fungi—can be used as biological warfare agents, but in practice, a handful of well-known agents are believed best suited for biological warfare purposes. Of these, the bacterium that causes anthrax is one of the most worrisome. The anthrax bacterium is highly lethal, easily disseminated in the atmosphere, and noncontagious. Military strategists typically dismiss contagious agents (those that can be transmitted from an initially infected person to an uninfected one) since they pose the risk of an uncontrollable epidemic, which could spread to the attacker's own population or troops.

Because of their ability to multiply within the host, even microscopic doses of biological warfare agents can kill. Kilogram quantities of anthrax bacteria, for example, could kill hundreds of thousands of people if effectively distributed, a casualty range comparable to that of a nuclear weapon. However, the effects of a biological weapons attack are highly variable and depend on a range of unpredictable factors. These include the type of agent used and dose received, the immune response of the targeted population, the efficiency of the aerosol-producing device, weather, and the timing and quality of medical treatment received by those affected.

Traditionally, biological weapons have been regarded as weapons of terror, not instruments for military operations. Apart from the moral stigma attached to the use of biological weapons, their delayed and unpredictable effects make them ill-suited for virtually all tactical military purposes.

Modest Barriers to Acquisition

The difficulty of producing chemical and biological weapons depends on the type, quality, and quantity of weapons desired. The most sophisticated chemical and biological weapons, involving the most lethal agents and the most effective dissemination systems, cost millions of dollars to produce and require well-trained scientists and skilled technicians to build them. If the weapons were intended for military use, they would generally need to be produced in large quantities and fashioned into durable, reliable devices. The financial and technical demands of such an effort are considerable, but they could be surmounted in time by any determined, moderately industrialized state.

However, less sophisticated but still quite effective chemical and biological weapons, such as those intended for terrorist use, can be produced at considerably lower cost and with much less difficulty. The basic science behind these weapons has been known for decades and is accurately described in a range of accessible scientific publications. Most materials and equipment needed to produce basic chemical and biological weapons have legitimate civilian applications and are available from commercial vendors. Some advanced scientific training and good laboratory skills are necessary to produce significant quantities of chemical and biological warfare agents, but training at the undergraduate college level is generally sufficient.

The greatest technical challenge involved in producing an improvised chemical weapon is to manage the chemical synthesis process without causing a harmful leak, accident, or explosion. For a biological weapon, the most difficult challenge is to design and produce a system of dissemination that will create an effective aerosol.

CBW Stockpiles

Chemical weapons have been stockpiled by many countries for most of this century, beginning with World War I. The United States stockpiled some 30,000 metric tons of chemical agents, which are now being incinerated at eight sites throughout the nation as well as on Johnston Atoll in the Pacific Ocean. Russia has pledged to destroy the chemical weapons stockpile it inherited from the USSR, but its effort has been delayed by financial difficulties. Russia declared a chemical weapons stockpile of about 40,000 metric tons, but some estimates of its true size range as high as 200,000 metric tons.

Most other large states with chemical weapons arsenals have pledged to destroy these stocks under the Chemical Weapons Convention (CWC), an international treaty approved in 1993. However, several states have either boycotted the CWC or have joined the convention but are still suspected of harboring clandestine chemical weapon programs. These states include China, Egypt, Iran, Iraq, Israel, Libya, Myanmar, North Korea, Syria, Taiwan, Vietnam, and the Federal Republic of Yugoslavia.

Despite the modest technical obstacles to biological weapons acquisition, the actual use of biological weapons has been exceedingly rare. Little is known about the secret biological warfare programs of most suspect countries. Western military experts believe that eight countries—China, Egypt, Iran, Iraq, Israel, Libya, North Korea, Russia, Syria, and Taiwan—have some form of offensive biological weapons program, although details are sketchy.

CBW Use in History

Harmful chemical and biological substances have been used for hostile purposes throughout history. From the assassin's poison, to the venom-tipped arrows of the Amazon Indians, to the plague-infested corpses catapulted by the Mongols over the walls of Kaffa (now in Ukraine) in the 12th century, to the smallpox-infested blankets given to Native Americans by British soldiers in the 18th century—all these instances, and many others like them, could be considered chemical or biological warfare if a sufficiently broad definition is adopted. But the age of weapons of mass destruction did not really dawn until World War I, when technological advancements reached the point where a single weapon could kill thousands of people.

Chemical weapons were used without restraint during World War I and caused an estimated 1.3 million deaths. The attacks began with Germany's use of wind-blown chlorine, but the technology advanced rapidly to artillery-fired chemical munitions. Chemical defenses advanced as well. By the end of 1915 most Allied troops on the Western Front possessed gas masks that could protect them from the asphyxiating effects of chlorine and phosgene. In July 1917 the Germans introduced a terrible new chemical weapon called mustard gas, which attacked the skin as well as the lungs and rendered the Allies' gas masks ineffective.

Chemical weapons exacted a terrible human toll during World War I and occasionally determined the outcome of individual battles. In the end, however, the unrestricted use of chemical weapons by both sides proved self-negating and did not determine the war's outcome.

The terrible, futile chemical warfare of 1915 to 1918 led the League of Nations to adopt the Geneva Protocol of 1925, which banned the use of chemical and biological weapons. Chemical and biological warfare has occurred only infrequently since then, but there have been a number of important violations. Spanish forces used chemical weapons in Morocco in 1925, Italian forces used them in Ethiopia in 1935 and 1936, and Japanese forces used chemical weapons in China between 1937 and 1945. Compared to World War I, these instances of chemical warfare were of modest scale and significance. By World War II (1939-1945), all of the major antagonists refrained from using their large stockpiles of chemical weapons. Their restraint arose mainly from a shared judgment that using these weapons would trigger a similar escalation by the opposite side, without decisively influencing the war's outcome.

Yet even as the storm clouds of World War II were gathering in the 1930s, Imperial Japan was opening new frontiers in the development of weapons of mass destruction. At the initiative of a group of enterprising Japanese officers with medical training, the Imperial Japanese government established the world's first biological weapons research program in 1932 in occupied China. Until the war's end this program, known as Unit 731, conducted gruesome medical experiments on Chinese and Russian civilians and prisoners of war (POWs). The experiments were designed to determine how naturally occurring diseases, including anthrax, plague, typhoid, smallpox, gangrene, tetanus, venereal diseases, tuberculosis, and frostbite could be used as military weapons, and to develop and field-test prototypes.

Although the program did not succeed in developing useful military weapons, it did produce and use a variety of crude biological weapons against Chinese civilians, mostly involving delivery by infected fleas and foodstuffs. After the war, the officers in charge of Unit 731 were not tried for war crimes; they avoided prosecution in exchange for providing the United States with data derived from their experiments.

CBW and the Cold War

Nuclear weapons and conventional armies were the main focus of the USSR and the United States during the Cold War, but both sides made substantial investments in their CBW capabilities as well. United States and Soviet military doctrine held that their military forces would “fight through” an opponent's CBW attacks, retaliate in kind, and if necessary escalate to nuclear weapons. Massive chemical arsenals were created, including vast quantities of the new, sophisticated, and exceptionally deadly nerve gases, such as VX and binary weapons. Binary weapons were developed to enhance the safety of the chemical arsenal. They consist of two or more chemicals that are harmless by themselves but when combined form a deadly chemical warfare agent.

Both superpowers also developed large-scale biological warfare programs and perfected the technology needed to disseminate pathogenic organisms as stable, respirable (capable of being inhaled) aerosols, a key technical threshold for an effective biological weapons capacity. By 1969 the U.S. military had become convinced that biological weapons were of little military value in the nuclear era, and the United States officially ended its offensive biological weapons program. United States government officials and military experts hoped the USSR would follow suit by renouncing its own biological weapons program as well.

With the United States and the United Kingdom, the USSR negotiated and signed in 1972 the Biological Weapons Convention (BWC), an agreement banning offensive biological warfare programs. The agreement, which the United States ratified in 1974, did not establish procedures to verify compliance with the convention.

It is now known that the USSR continued its large-scale biological weapons program in secret. Hints of this illegal program came to light in 1979 when international medical experts learned of a mysterious outbreak of respiratory anthrax in the Soviet city of Sverdlovsk, the site of numerous secret military facilities. More than 60 civilians and an unknown number of military personnel died. Although the subject of a decade-long cover-up and diplomatic controversy, the Russian government revealed that the Sverdlovsk anthrax outbreak had indeed resulted from an accident at an illegal biological weapons facility.

Russian President Boris Yeltsin pledged in 1992 that his government would terminate the germ warfare program, but the U.S. government and most international experts remain unconvinced that the program has in fact been ended. Some experts believe Russia has retained the facilities needed to produce a substantial arsenal of strategic biological weapons that could be delivered by intercontinental ballistic missiles (ICBMs), as well as a research program aimed at producing new biological warfare agents, including genetically engineered anthrax.

Chemical Weapons in the Middle East

The most extensive and deadly use of chemical weapons since World War I occurred during the Iran-Iraq war (1980-1988). In 1984 Iraq initiated the use of chemical weapons, primarily mustard gas, to compensate for Iran's superior manpower reserves. Iran also used chemical weapons against Iraqi forces, but the Iranian military was poorly prepared to produce and use chemical munitions effectively. Chemical warfare continued through 1988.

Iraq's use of chemical weapons did not alter the course of the war, but was tactically significant in a few battles. Led by Iraqi President Saddam Hussein, the government also used chemical weapons against its Kurdish citizens, who were inspired to rebellion during the war. Casualty figures from chemical weapons use are quite uncertain, but experts estimate that 45,000 Iranians died as a result of Iraq's attacks, while between 3000 and 5000 Kurds were killed.

In 1990 the international community again became acquainted with the Iraqi CBW threat when Iraq invaded Kuwait. As U.S. forces deployed to the Persian Gulf, U.S. military officials realized that the technologically superior U.S. military was poorly prepared for chemical warfare. But Saddam Hussein was deterred from using chemical or biological weapons in the Persian Gulf War, and Iraqi forces were soundly defeated in February 1991.

After the war the United Nations (UN) Security Council required Iraq to destroy its weapons of mass destruction and the facilities for producing them. A newly created UN Special Commission (UNSCOM) was charged with verifying this commitment through an unprecedented system of investigations and on-site inspections. However, Iraq has sought to conceal its special weapons programs and to undermine the UN inspection effort.

The UN inspections have uncovered a vast and surprisingly sophisticated CBW program in Iraq, including advanced nerve gas and anthrax weapons, and has overseen the destruction of much of it. Nonetheless, Iraq is still believed to possess substantial quantities of chemical and biological warfare agents as well as the equipment needed to produce more. The international dispute over Iraq's CBW program nearly led to punitive U.S. air strikes against Iraq in February 1998, a step that was narrowly averted by a last-minute compromise brokered by UN Secretary General Kofi Annan. But many experts doubt that Saddam Hussein's government will ever comply fully with its UN disarmament commitments.

Terrorism and the CBW Threat

There have been a handful of cases in history in which terrorist groups have used or attempted to use chemical or biological warfare agents, but most of these incidents have been of little significance. One incident, however, stands out: the nerve gas attacks carried out by the apocalyptic Japanese cult Aum Shinrikyo. In September 1994 the cult carried out a sarin attack in the Japanese town of Matsumoto, an event that went unnoticed by international intelligence agencies. Then, in March 1995, the cult carried out a much larger attack in the Tokyo subway, killing 12 people and injuring 5000. Most experts believe casualty levels would have been significantly higher if the cult had employed even a rudimentary dissemination system.

The cult manufactured its nerve gas in a secret production facility in the Japanese countryside, where it also carried out research into biological and other advanced weapons. Aum Shinrikyo demonstrated beyond any doubt that weapons of mass destruction were no longer exclusively controlled by major national governments and could be acquired by terrorist groups and others.

International Initiatives to Limit CBW

In 1993 the international community signed the landmark Chemical Weapons Convention (CWC). The CWC went well beyond the 1925 Geneva Protocol by prohibiting the possession and use of all chemical weapons, and by requiring signatory states to destroy all chemical weapons stockpiles. The CWC contains a comprehensive system for verifying compliance with convention requirements through detailed exchanges of data, regular on-site inspections, and challenge (surprise) inspections to investigate irregularities. A new international organization, the Organization for the Prohibition of Chemical Weapons (OPCW), was established in The Hague, Netherlands, to oversee implementation of the agreement. After a heated debate in the U.S. Senate, the United States ratified the CWC in April 1997, allowing the convention to enter into force that same month.

Since 1994, negotiations have been underway to add a verification protocol to the 1972 BWC. But many experts doubt that these talks will succeed in producing an effective biological weapons verification system, because the nature of such weapons makes them extremely difficult to monitor reliably. In addition, the biotechnology industry is concerned about the risks of industrial espionage perpetrated under the guise of treaty verification. Although work continues on the BWC verification protocol, some experts and officials are exploring other options for preventing biological warfare in the future, principally through efforts to further stigmatize biological warfare and to make possession or use of biological weapons a crime under international law.

CBW Risks of the Future

Most experts believe that an ever-increasing number of countries and terrorist groups will gain the technical capability to acquire and use chemical and biological weapons. But use of these weapons by hostile states or terrorist groups is not inevitable. Even when locked in bloody conventional wars, nations that have considered using these weapons have generally been deterred by the risk that their opponents would retaliate in kind or escalate the conflict elsewhere. Terrorist groups with the technical capacity to acquire and use a chemical or biological weapon have typically lacked an interest in doing so, while groups interested in such weapons have generally lacked the necessary technical skills.

Assessing future threats, however, involves more than simple extrapolation from past trends. In the case of chemical and biological weapons, it appears that the likelihood of use by both hostile states and terrorist groups is growing, and it is clear that even one such attack against an unprotected population could be devastating.

Ironically, some experts believe that the technological superiority of the U.S. armed forces is heightening the long-term risks of CBW use by states that wish to challenge the international status quo through aggression. Hostile states that hope to have a fighting chance against a U.S.-led military coalition, such as the one that defeated Iraq in 1991, may search for ways to compensate for the inferiority of their own conventional military forces. An obvious answer, and one of grave concern to U.S. military planners, is that such states might turn to an unconventional arsenal, most importantly chemical and biological weapons.

The threat of CBW use by terrorists is of an entirely different character. Terrorists have almost always chosen to kill fewer people than they are able to kill. The main reason is that traditional terrorist strategies seek to draw international attention to a cause without excessively antagonizing public opinion. For a variety of reasons this traditional model of terrorism appears to be changing in ways that make future acts of CBW terrorism more likely.

Some terrorist groups appear to be increasingly interested in causing massive casualties, a phenomenon that may stem from a rise in religiously inspired acts of violence, the emergence of new, more fluid terrorist cells, and the perception that traditional, low-casualty terrorist acts have lost the capacity to focus public attention. To date only the Japanese cult Aum Shinrikyo has combined the technical capability with the lethal intent required to carry out an act of CBW terrorism. But national security experts are increasingly concerned that more hostile groups will follow Aum's precedent and will do so with greater effectiveness than the cult displayed.

The Promise and Peril of Biotechnology

As the world struggles to cope with the threats raised by the scientific advances of a century ago, a new revolution in the field of biotechnology may have an even more profound impact on the scope and form of future human conflict. Since 1953, when biochemists James Watson and Francis Crick identified the structure of deoxyribonucleic acid (DNA, the genetic basis of all living organisms), the scientific understanding of biological and genetic processes has accelerated dramatically. This so-called "biotechnology revolution" has spawned new industries focused on manipulating human, animal, plant, and microbial genetics to create heretofore unattainable products and services, primarily in the medical area.

Some aspects of biotechnology have raised deep ethical questions, but most developments in the field are serving to advance the quality of human life. But like all scientific advances there is a risk that these new technological capabilities will be used for destructive purposes. In particular, developments in biotechnology are making it possible to design advanced biological warfare agents that could prove even more devastating to humanity than their naturally occurring cousins. For example, it might soon be possible for microbiologists to design and produce special pathogens of enhanced lethality, heightened resistance to medical treatment, predictable or controllable effects, or even the ability to infect people selectively, according to specific genetic characteristics.

This newly emerging science, if it is ever applied to weapons research, has the potential to revolutionize humankind's ability to destroy life, just as it is currently revolutionizing ways to save and enhance life. This is a scientific revolution every bit as profound as the dawning of the nuclear age, and one which is likely to command at least as much attention in the first half of the 21st century.