Chemical Terrorism Threats

views updated

Chemical Terrorism Threats

The Conflict

In the past five years, and especially since the September 11 terrorist attacks in the United States, there has been a heightened awareness of all forms of terrorism, including that of chemical terrorism, which often generates more fear amongst the public due to its nature. Chemical terrorism is the use by terrorists of toxic chemical agents to attack their targets.


  • The use of chemicals as weapons has a long history, but their first major appearance on the battlefield was during World War I, when agents such as chlorine and mustard were used extensively.
  • Chemical weapons were not used in World War II, but were used afterwards, such as during the Iran-Iraq War from 1980-88.


  • Although conventional explosives remain the weapon of choice for most terrorists, there are several reasons why terrorists might find chemical agents attractive, including the vulnerability of modern society to these weapons, their tactical flexibility, and the evidence that they are easier to acquire and deliver than most other unconventional weapons.
  • Large-scale chemical terrorism is possible, but it is not as easy as is often assumed.
  • Various measures can be taken to combat the threat, from both the prevention side, such as law enforcement and intelligence gathering, and the preparedness side, such as emergency planning and stockpiling antidotes.

Political and Religious

  • The most likely perpetrators of chemical terrorism that results in mass casualties are groups or individuals with characteristics such as the lack of a need for political support and a set of moral values permitting mass murder. The most likely group type to use chemical weapons is religiously motivated terrorists, including cults.
  • There have been many attempts, plots, and even several attacks using chemical agents.

The tragedy on September 11, 2001, when New York City and Washington, DC, were targeted by terrorists in hijacked commercial airliners, represented more than a terrorist attack. More American civilians died on this day than on any other single day in the nation's history, including a civil war and two world wars. The attack was a water-shed event in the annals of terrorism, proving once and for all that terrorists now have both the capability and the willingness to kill or maim thousands of innocent civilians. In addition, if they are willing to cause mass casualties, then we need to ask how they might accomplish this besides using explosives and hijacked aircraft. This brings us to a consideration of terrorists' use of various unconventional weapons. (Unconventional weapons, including chemical, biological, nuclear, and radiological, are those weapons that have not been widely used throughout the history of warfare and include almost any weapons besides explosives, incendiaries, and projectile weapons.) One of the most highly feared of these potentially devastating forms of violence is chemical terrorism, the use by terrorists of toxic chemical agents to attack their targets.

In the weeks following September 11, as fears of further al-Qaeda attacks grew, the possibility of a fresh assault using toxic chemicals received much exposure. Stores nationwide began selling out of gas masks, crop dusters were grounded, and television specials instructed viewers on how to seal off their homes from poison gas. The concern over chemical terrorism was then temporarily displaced by fears of bioterrorism as the anthrax attacks via the U.S. mail came to light in October 2001. Yet even with all the attention paid to the anthrax letters and the U.S. war in Afghanistan (a response to the September attacks), the prospect of chemical terrorism on the part of extremists like the al-Qaeda organization remains a concern at the highest levels of government. President George W. Bush (2001-), in his 2002 State of the Union Address, stated emphatically that " … the depth of their [the terrorists'] hatred is equaled by the madness of the destruction they design. We have found … [in Afghanistan] detailed instructions for making chemical weapons … "

Chemical terrorism includes attacks with chemical agents that states have developed for use in war (high-level agents), as well as contamination with toxic chemicals used commercially (low-level agents). In either case, these substances, when used by terrorists, are intended to incapacitate, injure, or kill human beings, often on a large scale.

Chemicals, together with radioactive and biological materials, inspire a particular sense of dread that one does not encounter with even the most destructive conventional weapons. They are invisible, silent killers against which most people feel impotent. Chemical terrorism brings with it the possibility of mass casualties, panic, and even widespread hysteria. Since an individual or small terrorist group could cause so much harm using chemical agents, chemical terrorism could be considered a form of asymmetric warfare (where one side in a conflict uses unconventional tactics, weapons, or strategy to negate the military strengths of the other). As such, it poses a danger to U.S. national security, since American bombers, tanks, and soldiers can do little to protect against unconventional terrorism. The threat is also a global one, as modern terrorists like al-Qaeda and Aum Shinrikyo have been known to operate across national boundaries and often have bases and targets in several countries.

Historical Background

History of Chemical Warfare

Employing chemicals as weapons is hardly a recent phenomenon. Chemicals have been used by states and other groups to hurt or incapacitate their enemies as far back as the Peloponnesian Wars (431-404 BCE) when Thucydides recorded the use of sulfur-based smokes and arsenic clouds. It was only with the technological advances of the twentieth century, however, that chemical weapons (CW) achieved the status of true weapons of mass destruction.

The first major chemical attack occurred during World War I (1914-18) at Ypres in Belgium. On April 22, 1915, the German army released copious amounts of chlorine gas from cylinders on the battlefield, causing at least 2,800 casualties. Both sides, however, quickly learned to take protective measures such as wearing gas masks, and chlorine soon became a relatively ineffective weapon. In July 1917, therefore, the Germans began to use a new agent called mustard, which after a brief delay affects the eyes and lungs, causing the skin to become extremely irritated and blister. A combination of this and similar agents and the delivery of chemicals by artillery shell made chemical warfare far more harmful than before. In total, a massive 124,000 tons of chemical agent munitions were delivered by both sides during World War I. Yet the use of chemicals resulted in only about 1.3 percent of total battlefield deaths in the war. Chemical weapons were far more effective because of the fear, confusion, and consequent loss of morale they caused than because of their lethal effects.

Despite the scorn towards chemical weapons displayed by most nations after the World War I, Italy, under the fascists, used mustard in bombs and spray devices during its invasion of Ethiopia in 1935-36. Also during the 1930s, the lethality of chemical weapons was greatly enhanced by the development of organophosphates (phosphorus-containing compounds often used in insecticides). This led to the creation of the so-called nerve agents such as sarin, soman, and later VX. Aside from Japan's use of World War I-era chemicals in China, however, none of the aforementioned chemicals were ever used on the battlefields in World War II (1939-45). The non-use of CW in World War II probably had much to do with the threat of retaliation, although several other factors may have come into play. World War II, however, did witness the deadliest use of chemicals in human history as millions of Jewish and other civilians were murdered by the Nazis using Zyklon B, a derivative from the civilian pesticide industry that released hydrogen cyanide gas.

During the Cold War, the United States and the Soviet Union stockpiled unprecedented amounts of chemical weapons—approximately 40,000 tons by the Soviet Union and 30,000 tons by the United States. Despite these formidable arsenals, neither superpower dared to use CW directly against one another during the Cold War, and in 1969 President Richard Nixon (1969-74) declared that the United States would not be the first side to use chemical weapons in any conflict.

Nonetheless, chemical weapons were utilized during the years of the Cold War. When Egypt intervened in the civil war in Yemen in the 1960s, it made use of chemical agents. The most widespread post-World War I use of chemical weapons against personnel occurred during the Iran-Iraq conflict from 1980 to 1988. Iraq, facing human wave attacks from neighboring Iran, used both nerve and blister agents on Iranian troops. Later in the war, Iran also employed chemical weapons, albeit minimally. Iraq found its chemical weapons fairly effective on the battlefield, but also viewed CW as a way to deter opposition to Iraqi leader Saddam Hussein's acts of intimidation towards neighbors in the Gulf region. By the time of the Gulf War of 1991 the U.S.-led coalition was extremely wary of Iraq's chemical arsenal and took measures to protect themselves through masks and protective clothing.

Whatever the present military effectiveness of chemical weapons actually is, one event showed the lethal efficiency of chemical weapons when used against civilians. In 1988 the Iraqi government used several types of chemical weapons against the Kurdish village of Halabjah. At least 4,000 civilians were killed in this attack.

Several attempts have been made by states to ban the use of chemical weapons. Both the Hague Conference of 1907 and the 1925 Geneva Protocol tried to forbid the use of chemical weapons (with various exceptions and exemptions), but these treaties did little to prevent the use or stockpiling of chemical weapons from World War I onwards. The Chemical Weapons Convention (CWC), which came into force on April 29, 1997, represents the next major step in chemical arms control in that it bans both the use and the production or possession of chemical weapons and makes provision for inspections in order to ensure compliance with the treaty. There are also voluntary efforts by like-minded states to prevent the spread of chemical weapons, such as the Australia Group, which attempts to control some of the trade in the precursors and equipment used to make chemical weapons.

Why Would Chemical Agents Be Attractive to Terrorists?

Why might terrorists find chemical weapons and agents attractive—in some cases even preferable to—conventional, nuclear, radiological, or biological weapons? Conventional weapons include almost any type of bomb or gun; nuclear weapons harness the power within atoms to cause devastating explosions; radiological weapons cause harm by emitting dangerous levels of radiation; and biological weapons use dangerous biological organisms to cause disease. Chemical agents, when used effectively, have the potential for causing far more casualties than any conventional explosive and may appear, at least on the surface, attractive to any group with this end in mind. There are, however, many reasons why terrorists would choose conventional over unconventional weapons, even if they want to cause large numbers of casualties. Explosives and hijacked planes, for instance, are cheaper, more reliable, are generally easier to acquire and use, and can cause sufficient destruction to achieve terrorist goals. Why then is there so much concern about terrorists getting their hands on chemical agents?

Three of the advantages for terrorists conducting a chemical attack will be examined: the physical and psychological vulnerability of targets; the flexibility of these weapons; and the growing ease with which these agents can be acquired and utilized.

Vulnerability. Chemical agents work best when concentrated over a limited area. Modern society is largely made up of densely populated areas with complex transportation networks carrying thousands of passengers at any given point in time. Large cities are thus particularly susceptible to a chemical attack, making chemical agents an ideal weapon to those terrorists seeking to maximize casualties.

On the psychological level, anthropologists have observed an almost universal loathing for poisons and impurities. People often display a disproportionate amount of fear for anything that can enter the body unnoticed and harm them from within. Historical evidence from the use of chemical weapons in war indicates that these weapons cause considerable panic and confusion. They are also faster acting than biological agents, while inducing similar psychological effects of contamination. A significant goal of any terrorist act is to instill fear in a wider population, often referred to as the secondary target (where the primary target is the set of direct victims of an attack). Therefore, in a civilian context, where any event is magnified by the media, a chemical attack is likely to give terrorists all the terror and propaganda they seek.

Flexibility. While not nearly as wide ranging in applications, or as easy to use as conventional weapons like guns and bombs, chemical agents have certain tactical advantages over other weapons of mass destruction (WMD). First of all, they are the only type of unconventional weapon which has a decent track record—military officers from World War I onwards have had substantial success causing casualties with chemical agents. While all weapons of mass destruction are inherently indiscriminate in their action, chemical agents can also be used in a more controlled fashion, involving more discriminate attacks on limited targets, such as a specific building. This would be impossible with, for instance, a nuclear explosive. Another attractive aspect is that a terrorist need not go to all the trouble of acquiring an agent that has been weaponized by states, such as VX, in order to cause mass casualties. There is a much broader range of chemicals, including certain classes of pesticides and industrial chemicals, that still have toxic effects, even if these are less than military-grade CW agents. If terrorists are already set on using unconventional weapons, the flexibility and success rate of chemical weapons may influence them to choose them over biological, nuclear, or radiological agents.

Relative Ease of Acquisition and Use. At least on a theoretical basis, chemical agents are easier to deliver to their targets than are biological or radiological agents. Certain volatile chemicals such as sarin will vaporize at room temperature and fill an enclosed space with toxic fumes. These and other natural properties of certain chemicals, combined with increases in terrorists' capability to acquire and use these weapons, make chemical agents especially suitable for the terrorist who wants to cause maximum mayhem with minimal effort using a weapon of mass destruction.

One factor in the increasing chemical capability of terrorists is the access to dangerous chemicals. There is the concern that terrorists will acquire either chemical agents or completed chemical weapons from countries with unsecured storage facilities. The primary concern here is the states of the former Soviet Union, which produced thousands of tons of chemical agents and weapons. Lapses in discipline and morale of underpaid soldiers and scientists in this region since the collapse of the Soviet Union make it possible that at least small amounts of these materials have been or will be stolen and smuggled to terrorist groups. While small amounts of chemical materials and munitions are insufficient for use in a state-level program, they may be perfectly suitable for a terrorist attack. Terrorists may not even need to procure materials from state-level programs; the growth of advanced chemical industries, even in less-developed countries, means that the basic building blocks of many toxic chemical agents are easily found in any country with commercial chemical production.

Another recent development is the spread of the 'how to' of chemical weapons. The formulae and production processes for toxic chemicals have always been well known among the scientific community. The difference now is that specific details for developing these agents are being made accessible to anyone who is adept at using the Internet, and this presumably includes many terrorist groups and violent individuals. In addition to chemical materials leaking out of the former Soviet Union, there is the danger of terrorist groups recruiting or hiring chemists who used to work in the Soviet chemical weapons programs, but are now unemployed or unpaid in the cash-strapped successor republics.

Advances in technology may aid those terrorists who decide to develop their own agents. If they obtain the correct precursor chemicals, they can make use of new miniaturized chemical production equipment to produce these agents on a fairly large scale in tiny facilities like basements.

The easiest way for a terrorist group to acquire a chemical weapons capability is to be given one by a state. Several states that are known or suspected to have chemical weapons programs of their own—such as North Korea, Iran and Libya—have also been accused of sponsoring terrorism. Although there is no proof that any such transfer has occurred, government officials fear that these countries may make nuclear, chemical, or biological agents, and perhaps even operational weapons, available to their terrorist proxies.

Who Is Most Likely to Use Chemical Weapons?

It would appear that a relatively small subset of terrorists would go to all the trouble to launch a chemical attack rather than detonate a large conventional bomb. There are those for whom the factors making chemical terrorism attractive outweigh the greater ease of using conventional weapons, the moral prohibitions on mass casualties, and the costs in terms of lost support and retribution.

In the past decade, terrorist attacks seem to have become bloodier. The Tokyo subway sarin attack of 1995, the Oklahoma City (1995) and East African bombings (1998), and finally the attacks on the World Trade Center and the Pentagon in 2001 have all shown that terrorists have become more willing to cause mass casualties. In the 1980s noted terrorism scholar Brian Jenkins proclaimed that, "[t]errorists want a lot of people watching, not a lot of people dead." It seems that now they want a lot of people watching and a lot of people dead.

Scholars such as Bruce Hoffmann and Jessica Stern have associated this increased violence with the rise of religion-based terrorist groups. These are fundamentalist religious groups representing either extremist versions of the world's major religions or new, obscure religious beliefs, often in the form of cults. Islamic Jihad and Aum Shinrikyo are examples of such groups. Hoffmann, Stern, and others have further identified terrorist groups or individuals motivated by religion as the most likely to use weapons of mass destruction. They give various reasons for this. Religious terrorists often do not have a political constituency and are therefore less concerned about losing public support if they use weapons of mass destruction. They have radically different moral values, dehumanizing their perceived enemies and often viewing violence as a divine duty. They are sometimes even willing to inflict this violence on a large scale. Religious terrorists have also been known to seek to obliterate their enemies rather than make a symbolic point.

Several religious groups, particularly cults, have been known to display an apocalyptic outlook—they want to bring about the end of the world and may view weapons of mass destruction as the best way to do this. Certain aspects of unconventional weapons may make them especially attractive to terrorists motivated by extreme religious beliefs. For example, the very idea of bringing about death and panic through a silent, invisible toxic cloud could fit a cult's vision of divine punishment better than a car bomb. Furthermore, cults often have ample resources in terms of finances and sometimes have members with technical expertise.

It may be that the most likely perpetrators of mass-casualty chemical terrorism would be religiously motivated terrorists, or terrorists who share many of the characteristics of these groups. For more limited chemical attacks, there is a much bigger pool of potential perpetrators.

Past Chemical Terrorism Incidents

The Monterey Weapons of Mass Destruction Terrorism Database records 230 politically or ideologically motivated incidents involving chemical agents from 1945 to January 2002. Only 35 of these incidents were hoaxes, pranks, or solely threats. The remaining 195 incidents include uses, possessions, and plots by subnational groups or individuals involving chemical agents. Chemical agents are by far the most common type of agent utilized when considering all similar incidents, with 195 chemical incidents compared to the mere 66 of the next most common agent type, biological agents.

The story of chemical terrorism, however, is made up of more than just numbers. The first major case of modern chemical terrorism occurred when the Avengers, a group of Jewish extremists bent on revenge, poisoned German POWs in 1945 (see sidebar "Avenging Israel's Blood"). In the 1960s the right-wing group known as the Minutemen also took an active interest in chemical weapons. Believing they were defending the United States from a communist takeover, they gathered literature relating to producing and disseminating nerve agents, and their leader, Robert Bolivar DePugh, alleged that he had made homemade nerve 'gas' and tested it on his dog with fatal results.

An unconfirmed report notes that in Vienna in 1975, German entrepreneurs were arrested while attempting to sell the nerve agent tabun to Palestinian terrorists. The late 1970s and early 1980s also yielded two examples of deliberate chemical contamination. In 1978 the Arab Revolutionary Command used liquid mercury to contaminate Israeli citrus fruit destined for Europe, causing casualties in at least three European countries and leading to a reduction of at least 40 percent in Israeli orange exports. In September 1982 seven people died in Chicago, Illinois, from taking cyanide-laced Tylenol tablets. The culprit of this poisoning was never located, and the attacks spawned a host of copycat incidents. To some extent these attacks were responsible for the later development of tamper-resistant packaging for consumer products.

Right-wing extremists also dabbled with chemical terrorism during the 1980s. In addition to the instructive case of the Covenant, the Sword, and the Arm of the Lord (see sidebar), court testimony in 1990 by members of the skinhead organization known as the Confederate Hammerskins revealed that the group had plotted to pump cyanide into a synagogue. In Asia the Liberation Tigers of Tamil Eelam (LTTE), a rebel organization in Sri Lanka, have been accused of using 'poison gas' and other chemical agents on at least three occasions between 1990 and 1995.

Aum Shinrikyo

The event having possibly the greatest impact on the public perception of the potential for terrorist use of chemical weapons was the March 20, 1995, Tokyo subway attack by the Japanese cult Aum Shinrikyo. The attack was carried out simultaneously on five separate subway trains and the cult utilized the nerve agent sarin, which it had manufactured in its own laboratories. Cult members used sharpened umbrella tips to puncture plastic bags containing sarin and then fled. The attack brought to worldwide prominence the deadly designs of this apocalyptic organization and resulted in twelve fatalities, 1,039 injuries, and at least 4,000 people with psychosomatic symptoms (the so-called 'worried well').

Since the early 1990s, the cult had been attempting to overthrow the Japanese government and impose a bizarre theocratic state. The cult was dominated by Shoko Asahara, a leader who promulgated apocalyptic visions. Asahara soon became fascinated by chemical weapons and initiated a program to develop several warfare agents. Aum scientists managed to synthesize sarin, tabun, soman, VX, mustard, and hydrogen cyanide. When it came to mass production, however, their results were poor and the cult succeeded in producing only about 30 liters of sarin in total. Although Aum also pursued biological, nuclear, and conventional weapons programs, its chemical operations were by far the most successful.

It is worth noting that the group produced chemical (and other) weapons for both strategic reasons—to overthrow the state and bring about Armageddon—and also at times for tactical ones, such as to dispose of enemies and divert police from raiding Aum's headquarters.

The Tokyo attack was neither the first nor the last attempt by Aum to employ dangerous chemical agents. The Monterey Chronology of Aum Shinrikyo's CBW Activities (available online at reveals that between 1990 and 1995, Aum attempted several chemical attacks using sarin, VX, and phosgene. These were mostly aimed at assassinating individual enemies of the cult, the results of the attacks ranging from abject failures to murder. Before the subway attack, Aum had used sarin on a larger scale in June 1994 in the town of Matsumoto, killing seven people and injuring 144 in an attempt to assassinate judges ruling against the cult. Even after the subway attack, as the cult was being hunted down by Japanese police, Aum tried to set off devices that would react to release deadly hydrogen cyanide gas.

At first glance, the case of Aum Shinrikyo has ominous implications. Aum intended to kill thousands of people and came extremely close to doing so, and had succeeded in developing a large variety of chemical and other agents. Aum's use and possession of chemical weapons came as a total surprise to Japanese law enforcement and intelligence agencies.

On closer analysis, however, the case of Aum Shinrikyo may not be the vanguard of chemical terrorism that it may at first appear. Aum was an almost unique terrorist organization. With an estimated 40,000 followers, its membership was extremely large, and it had extensive financial resources (perhaps as high as US$1 billion) and many highly skilled personnel. It invested five years' worth of research and resources into developing chemical weapons. Yet all this investment and dedication yielded surprisingly limited results with respect to agent quality and delivery capability. Its sarin attack on March 20, 1995 used the rather crude delivery method of puncturing plastic bags filled with sarin using sharpened umbrella tips. Moreover, the attack caused limited fatalities, mostly because the sarin was diluted. While their case certainly deserves close attention, it is doubtful whether there will be many terrorist groups with the same capabilities as Aum.

Nevertheless, the Tokyo incident certainly changed the way the world viewed terrorism—no longer were the victims of terrorist attacks limited to several unfortunate individuals or a few hundred airplane passengers. The prospect of true mass-casualty terrorism was brought home to many for the first time. It was felt by many that the Tokyo attack removed the taboo against the use of weapons of mass destruction by terrorists, thus erasing any psychological barrier to their use which had existed previously. In other words, what had once only been a possibility was now a reality. People realized that unlike states, most terrorists have no defined "return address," and cannot be deterred from using WMD by threats of massive retaliation in kind.

The Tokyo incident arguably served as the catalyst for the widespread anxiety over terrorist use of weapons of mass destruction and led to a dramatic increase in U.S. government funding and attention to the problem. This heightened attention may also have made various governments particularly sensitive to the potential for chemical terrorism. In 1998, following the terrorist bombings of the American embassies in East Africa, the United States took the dramatic and controversial step of using cruise missiles to destroy the Al-Shaifa plant in Sudan, with the justification being that the facility was being used to produce chemical weapons destined for terrorists.

Recent History and the Future

Osama bin Laden, al-Qaeda, and Chemical Terrorism

The September 11 attacks in the United States focused the world's attention on one terrorist network in particular, the al-Qaeda organization, and its notoriously anti-American leader, Osama Bin Laden. Bin Laden and the al-Qaeda network, which is an umbrella organization consisting of various groups and many largely autonomous cells, have been conducting an ongoing terrorist campaign against the West since at least 1998. Al-Qaeda has been linked with the East African embassy bombings, the assault on the USS Cole in Yemen in October 2000, and finally the horrendous attacks on the World Trade Center and Pentagon on September 11, 2001. Thus far, al-Qaeda has accomplished all its objectives using conventional weapons, but several concerns have been raised that it may resort to chemical terrorism.

These concerns are well founded. Bin Laden himself has on several occasions expressed his interest in acquiring weapons of mass destruction. According to a variety of newspaper reports, three meetings took place between senior members of al-Qaeda and foreign governments between 1997 and 1998, at which al-Qaeda's acquisition of chemical weapons was on the agenda. On 8 July 1999, in an article entitled "Islamic Group Said Preparing Chemical Warfare on the West," the Italian newspaper Corriere della Serra reported that members of the World Islamic Front Against Jews and Crusaders—which was founded by bin Laden and is part of the al-Qaeda network—had purchased three chemical and biological agent production

[This text has been suppressed due to author restrictions]

facilities in the former Yugoslavia in early May 1998. The article also described a similar factory that had been built near Kandahar in Afghanistan. Kenneth Katzman, a Middle East analyst and terrorism expert at the Congressional Research Service was quoted by the Washington Post (July 29, 1999), as saying that "we have to assume that he [Bin Laden] has some rudimentary chemical capability."

Various incidents seem to confirm these assertions. Shortly after the September 11 attack, it was reported by the London Sunday Telegraph (September 16, 2001) that earlier in 2001, German police had foiled a plot by an al-Qaeda cell to attack the European Parliament building in Strasbourg, France, with sarin nerve agent. al-Qaeda documents found in Afghanistan describe tests on animals with various chemical agents including cyanide gas. A group of men with possible links to al-Qaeda was also arrested in Rome, Italy, in February 2002 in possession of a cyanide-containing compound and maps of the water network in the area around the U.S. Embassy.

While there is no incontrovertible evidence that Osama bin Laden actually has the ability to conduct chemical terrorism on a large scale, there is no doubt that his organization has been exploring the possibility of conducting a chemical attack of some kind. Skeptics about the chemical threat from al-Qaeda are urged to pay heed to the recent remark by Eric Croddy in his book Chemical and Biological Warfare: A Comprehensive Survey for the Concerned Citizen(2002), "As recent experience has shown, however, it is dangerous to underestimate the resourcefulness of a determined adversary."

Prospects for Chemical Terrorism

From the revenge poisonings of Avenging Israel's Blood to Aum Shinrikyo's chemical attacks and al-Qaeda's quest for a toxic arsenal, chemical terrorism presents a very real and very frightening threat. Yet, in the words of Jessica Stern in her 1999 book, The Ultimate Terrorists, "Catastrophic risks are disproportionately feared," and in spite of the media hype and public anxiety, this threat needs to be placed in its proper context. For example, many people tend to overlook the fact that in addition to acquiring a chemical agent, a terrorist must still deliver it efficiently in order to cause mass casualties. Although crude delivery methods can be utilized—especially in enclosed areas—such as the plastic bags in the Tokyo subway attack, the most effective means of dispersal is to aerosolize the agent. This requires not only a knowledge of chemistry, but also of engineering, and took several years even for states, with all their resources, to perfect. This requires much more effort and resources than most terrorist groups have available.

While it is true that some factors, such as the dissolution of the former Soviet Union and the rise of religious groups, seem to be making chemical terrorism a slightly less challenging endeavor, this does not mean that chemical terrorism is a simple task. Even contaminating water supplies is not as simple as dumping toxic chemicals into a reservoir—dilution and water treatment will render many agents harmless and quality checks can also identify contaminants before the water gets to the public. Most experts argue that only remote water supplies, or smaller parts of a large water network, are vulnerable, lessening the chance of large numbers of casualties. As for states giving terrorists working chemical weapons, this would indeed make a chemical attack easier. The threat of retaliation from the target country and the international community, however, would dissuade all but the most foolish of states from chemical terrorism.

In the non-technical realm there are several moral obstacles that need to be dealt with before anyone will carry out a mass-casualty chemical attack, and even incentives as strong as religion may not be enough to overcome psychological restraints such as society's rejection of murder or the notion that women and children must be protected and not harmed.

The overall likelihood of chemical terrorism depends on too many factors, including unique variables like the psychological makeup of individual terrorists, to make any predictions about the prevalence of this form of terrorism in the future. Many scholars such as Jonathan Tucker and Jessica Stern, however, believe that should terrorists engage in terrorism using unconventional weapons, they are most likely to employ chemical weapons. Furthermore, these attacks most often will be on a relatively small scale with lower-end agents. An example of this would be using a chemical agent inside a single building or contaminating individual types of foodstuffs. This does not mean that the large-scale use of a warfare agent like sarin or VX will not be seen again, but rather that this possibility is often overstated.

Combating Chemical Terrorism

The extent of the threat of chemical terrorism may not be known with any certainty, but the threat from terrorist groups is sufficiently feared that governments and the international community are devoting resources to combating it. Many of the standard counterterrorist measures apply equally well to terrorists attempting chemical attacks. These include intelligence gathering, law enforcement, diplomatic measures, and sometimes even military activities.

Some steps can be taken to combat chemical terrorism in particular. Stopping the proliferation of chemical weapons would make it more difficult for terrorists to get their hands on these agents; however, international measures such as the Chemical Weapons Convention and the Australia Group are mainly structured to prevent states from obtaining chemical weapons. They are therefore not designed to prevent or monitor the transfer of the smaller amounts of chemical agents that terrorists would seek. On the technology front, there are detectors that can provide early warning of a chemical attack, although these are not yet reliable enough for widespread use across an entire country. One of the best ways to combat chemical terrorism is to be prepared in order to minimize casualties should an attack occur. Both nerve and blood agent exposure can be treated if antidotes are administered quickly enough. Having sufficient antidotes, decontamination equipment, and trained emergency personnel in place can vastly reduce the number of fatalities in a chemical attack.

After Aum Shinrikyo's Tokyo subway attack and the Oklahoma City bombing in 1995, the U.S. government started paying much more attention to chemical and other forms of unconventional terrorism. Federal spending on defense against terrorism using weapons of mass destruction increased more than ten times from $130 million in 1997 to $1.45 billion in 2000; President Bill Clinton (1993-2001) issued Presidential Decision Directives (PDDs) in both 1995 and 1998 structuring government reaction to this kind of attack; in 1996 Congress passed the "Defense Against Weapons of Mass Destruction Act" (which became known as the Nunn-Lugar-Domenici Program) to train first responders to deal with a weapons of mass destruction attack; numerous organizations such as a Metropolitan Medical Response System were created to help manage the effects of an attack; and a national pharmaceutical stockpile was created, which in the event of a chemical attack would provide antidotes and medical equipment where needed. Some commentators have criticized these federal programs by calling them uncoordinated and often redundant. It is hoped that the new Office of Homeland Security, formed in reaction to the September 11 attacks, will be able to better coordinate these efforts.


The existence of groups and individuals who are actively pursuing a chemical capability and who seek to use it to inflict mass casualties can no longer be disputed. Eventually one of these groups may succeed in their endeavors. It is thus of little surprise that Western publics and their government officials have become particularly concerned about the threat of chemical terrorism, especially after the terrible events of September 11.

In order to develop and deliver a chemical agent that causes a large number of casualties is far more difficult than most people realize, and conventional weapons are still preferred by most terrorists. We should not, then, overstate the likelihood of chemical terrorism and cause undue alarm. Rather, we should continue the concerted effort to locate and apprehend terrorists and, in case this fails, to prepare to deal with the aftermath of a large-scale terrorist attack. In this way, we can minimize both the psychological and physical effects of this frightening form of terrorism.


Croddy, Eric, with Clarisa Perez-Armendariz and John Hart. Chemical and Biological Warfare: A Comprehensive Survey for the Concerned Citizen. New York: Copernicus Books, 2002.

Falkenrath, Richard A., et al. America's Achilles Heel: Nuclear, Biological, and Chemical Terrorism and Covert Attack. Cambridge, MA: MIT Press, 1998.

Gurr, Nadine, and Benjamin Cole. The New Face of Terrorism: Threats from Weapons of Mass Destruction. London: I.B. Taurus, 2000.

Hoffmann, Bruce. "Terrorism and WMD: Some Preliminary Hypotheses," The Nonproliferation Review. vol. 4, no. 3 (Spring-Summer 1997).

Jenkins, Brian. Will Terrorists Go Nuclear? Santa Monica, CA: Rand Corporation, 1975.

Kaplan, David E. and Andrew Marshall. The Cult at the End of the World. New York: Crown Publishers, 1996.

Lloyd, Anthony. "Scientists Confirm bin Laden Weapons Tests," Times (London), December 29, 2001.

Olimpio, Guido. "Islamic Group Said Preparing Chemical Warfare on the West," Corriere della Sera, July 8, 1998.

Roberts, Brad, ed. Terrorism with Chemical and Biological Weapons: Calibrating Risks and Responses. Alexandria, VA: Free Hand Press, 1997.

Stern, Jessica. The Ultimate Terrorists. Cambridge, MA: Harvard University Press, 1999.

Tucker, Jonathan B., ed. Toxic Terror: Assessing Terrorist Use of Chemical and Biological Weapons. Cambridge, MA: MIT Press, 2000.

Zanders, Jean Pascal. "Assessing the Risk of Chemical and Biological Weapons Proliferation to Terrorists," The Nonproliferation Review, vol. 6, no. 4 (Fall 1999).

Gary A. Ackerman


1915-19 During World War I the first widespread use of chemicals as weapons occurs. Agents used include chlorine gas and later, mustard.

1930s Nerve agents are developed, arising out of research on organophosphates.

1946 Avenging Israel's Blood, seeking revenge for theHolocaust, poisons food eaten by German soldiers in an American prisoner of war camp in Nuremberg, Germany.

1945-1990s Both the United States and the SovietUnion produce tens of thousands of tons of chemical weapons during the Cold War, but never use them.

1980-88 During the Iran-Iraq War, Iraq uses vast amounts of chemical weapons against Iran. Later in the war, Iran retaliates with a much smaller number of chemical weapons.

1988 The government of Iraq employs chemical weapons against Kurdish civilians within Iraq. More than 4,000 people are killed in an attack on the village of Halabjah.

1991 The U.S.-led coalition forces in the Gulf War take precautions against possible chemical weapons use by Iraq.

March 1995 Aum Shinrikyo, a violent Japanese cult, releases the nerve agent sarin into the Tokyo subway system, killing 12 people and injuring about 1,000. This attack forms part of a long string of chemical attacks by the cult.

1996 The U.S. Congress approves the training and equipping of local emergency services in the country's largest cities to deal with an attack using weapons of mass destruction. This becomes known as the Nunn-Lugar-Domenici Program and includes preparation for chemical terrorism.

April 1997 The Chemical Weapons Convention comes into force, outlawing the possession, production, and use of chemical weapons and many of their direct precursors.

September 2001 Terrorists fly hijacked airplanes into theWorld Trade Center and the Pentagon, killing thousands of civilians. These attacks spark fears of terrorist use of weapons of mass destruction. There are concerns that al-Qaeda, the terrorist group believed to be behind the attacks, is in possession of chemical weapons.

October 2001 President George W. Bush forms the Office of Homeland Security to protect the United States against terrorism, including chemical terrorism.

Poem on Chemical Attacks

Gas! GAS! Quick, boys!—An ecstasy of fumbling
Fitting the clumsy helmets just in time,
But someone still was yelling out and stumbling
And flound'ring like a man in fire or lime.—
Dim through the misty panes and thick green light,
As under a green sea, I saw him drowning.
In all my dreams before my helpless sight
He plunges at me, guttering, choking, drowning.

from Dulce et Decorum Est, by Wilfred Owen, 1918.

Available online at


The Bhopal incident occurred on December 3, 1984, in Bhopal, India, when methyl isocyanate, a toxic industrial chemical used in insecticide production, leaked out of the Union Carbide plant. Jessica Stern in The Ultimate Terrorists(1999) lists the number of dead as 4,000 with 11,000 injuries. The Indian government alleged the incident to be an accident that was the result of inadequate safety measures on the part of the Union Carbide Company. Even though Union Carbide agreed to a settlement compensating victims, its own inquiry and a separate investigation performed on its behalf by Arthur D. Little, Inc. concluded that the toxic release was an act of sabotage. A disgruntled employee, presumably seeking only to hamper production, connected a water hose to a tank of methyl isocyanate, leading to the disaster. Although the Bhopal tragedy does not really qualify as terrorism, since the perpetrator did not intend to cause so many deaths, it does highlight the danger that even a single individual can pose when dealing with toxic chemicals.

Properties of Chemical Weapons

  • Chemical weapons are made from more basic chemicals called precursors , many of which have legitimate uses in industry.
  • Just possessing a chemical agent does not make it a usable weapon—the agent must be put together with a delivery system capable of causing harm. That is, it must be weaponized .
  • The persistence of a chemical weapon refers to the length of time that the agent contaminates the immediate environment after release. For example, hydrogen cyanide is not very persistent in the open air, as it disperses very quickly.
  • Chemical weapons are very rarely gases at room temperature. Rather they are often used in the form of tiny droplets of liquid called aerosols that float in the air. This is why we don't say 'mustard gas' or 'sarin gas' but rather mustard or sarin.
  • Many chemical weapons are dangerous to make, especially in large quantities, and require specialized equipment. This, however, is not always the case for small-scale production.

Types of Chemical Weapons

There are four classes of chemical weapons that have been used by states in the past and could be used by terrorists:

Choking Agents include: chlorine, phosgene (CG)

  • Act on the airways and lungs, causing inflammation and in high enough doses leads to suffocation.
  • Responsible for so-called 'dry land drowning' in World War I.
  • Nonpersistent gases.

Blister Agents (Vesicants) include: mustard (H, HD), Lewisite (L)

  • Act on the skin, eyes and airways, causing blisters on the skin after some delay and affecting breathing. Also affects the whole body.
  • Mustard was very commonly used in World War I, causing many injuries but relatively few fatalities.
  • Persistent liquid that gives off vapors.

Blood Agents include: hydrogen cyanide (AC), cyanogen chloride (CK)

  • Usually inhaled or ingested—once absorbed into the body, it shuts down the functioning of cells and causes rapid death at low dosages.
  • Nonpersistent gas or liquid giving off vapors.

Nerve Agents include: sarin (GB), tabun (GA), soman (GD), VX

  • Most toxic agents.
  • Enter the body through skin, eyes, or lungs and quickly lead to seizures, convulsions and, if untreated, death.
  • G-agents: nonpersistent liquids and vapor; VX: persistent liquid.

Avenging Israel 's Blood

After World War II a group of Jews calling themselves Avenging Israel's Blood (Dahm Y'Israel Nokeamor DIN) plotted to take revenge on Germans for the murder of six million Jews during the Holocaust. Avenging Israel's Blood was led by the former partisan Abba Kovner, who formulated the group's ideology of vengeance. In 1945 DIN developed Plan A, which involved poisoning water supplies across Germany in order to kill hundreds of thousands of Germans, civilians included. Plan A was later abandoned in favor of Plan B. This called for the contamination of the food consumed by German POWs in camps holding German soldiers. Plan B was scaled down to an attack on Stalag 13, an American prisoner of war camp for SS soldiers near Nuremberg. On April 13, 1946, three members of Avenging Israel's Blood spread a mixture of glue and arsenic onto loaves of black bread eaten almost exclusively by the German inmates.

A German newspaper reported that 2,283 inmates out of 15,000 fell ill after eating the tainted bread, and 207 of those were hospitalized, with no known fatalities. DIN sources estimated that 4,300 people were sickened, 1,000 hospitalized, and that 700 to 800 of those hospitalized were paralyzed or died within weeks of the incident.

Avenging Israel's Blood is in many ways a rather unique organization in that it was not motivated by politics or religion, but solely by revenge. It did, however, share characteristics with many religious fanatics, such as seeking redemption through violence, a disregard for personal safety, and the dehumanization of its victims. All of these factors allowed it to consider inflicting mass casualties, perhaps indicating a heightened danger for mass-casualty terrorism among heavily brutalized communities.

The Covenant, Sword, and the Arm of the Lord

In 1985 federal law enforcement authorities found a small survivalist group called the Covenant, Sword, and the Arm of the Lord (CSA) in possession of a drum of potassium cyanide. CSA apparently intended to poison the water supplies of major US cities. Led by James Ellison, CSA based its ideology on the Christian Identity movement, holding anti-Semitic, racist, and apocalyptic beliefs. It also plotted to overthrow the U.S. government. CSA devised the water poisoning scheme in the belief that it could bring about the return of the messiah more quickly by punishing unrepentant sinners. The plot failed when its compound was raided by U.S. government officials, although the amount of cyanide they possessed would in any case have been too small to cause any harm to the water supply of a major city.

This case has several interesting aspects with regards to the prospects for chemical terrorism. The first and perhaps most relevant point is that the group's only objective in using cyanide was mass murder rather than changing government policy. Second, the group believed it was on a divine mission and was not concerned with offending a broader constituency. Third, the CSA chose an industrial chemical (potassium cyanide) instead of trying to develop a more toxic agent like sarin. The fourth point is that the CSA was easily penetrated by law enforcement—today similar groups are far more careful.

After the first World Trade Center attack in 1993, it was widely believed that the terrorists had placed cyanide-producing compounds in their bomb. There is no evidence to suggest that this was the case, but Ramzi Yousef, the leader of the group that perpetrated the bombing, later disclosed to a U.S. Secret Service agent after he was captured that his original intent was to include cyanide in the bomb. Fortunately, according to the testimony of Brian Parr in Yousef's trial (United States of America v Ramzi Ahmed Yousef and Eyad Ismoil, S1293CR.180 [KTD], October 22, 1997, pp. 4730-4731), Yousef decided that "it was going to be too expensive to implement."

The most infamous cases of chemical terrorism occurred in the mid-1990s with the actions of Aum Shinrikyo, the Japanese doomsday cult, which will be discussed in more detail later. In 1997 authorities raided the home of James Dalton Bell, an antigovernment activist, and discovered a variety of chemicals. Mr. Bell had apparently admitted to friends that he had produced a quantity of sarin nerve agent. On August 6, 1997, another lone perpetrator named Valery Borzov was arrested in Moscow, Russia, for trying to sell homemade mustard agent. Abortion clinics seem to have become popular targets for attacks using chemicals in the latter half of the 1990s, with several incidents in 1998 involving butyric acid, a mildly toxic and very foul-smelling chemical.

The cases described above are only a small percentage of the total of recorded terrorist incidents involving chemical agents, but they are sufficient to demonstrate the broad variety that exists within chemical terrorism. There are incidents involving large, military-style groups as well as those perpetrated by individual extremists. The chemicals used range from extremely lethal warfare agents like sarin to common, commercially available chemicals, like potassium cyanide. Delivery methods are diverse, from food contamination to releasing toxic vapor. It is worthwhile to note that of the groups listed that acted or plotted to bring about mass casualties with chemical agents, almost all of them were religiously motivated or shared many traits with religious terrorists.

Number of Chemical Incidents (Including Hoaxes) Involving Sub-national Actors, 1975-2000

About this article

Chemical Terrorism Threats

Updated About content Print Article