The Political and Emotional Power of Chemical Weapons

Chemical weapons elicit a very specific emotive and political response from populations, namely, anxiety. What are the drivers behind the fears surrounding chemical weapons? 

“War, like revolution, is founded upon intimidation. A victorious war…destroys only an insignificant part of the conquered army, intimidating the remainder and breaking their will…Terror…kills individuals, and intimidates thousands”.

Writing in 1920, Leon Trotsky thus attributed the power of war and terrorism to its psychological effect. The ability to intimidate and coerce is the key strategy in a world in flux; fear and uncertainty are the weapons of choice for terrorist groups. The observation that terrorists endeavour to kill few and create fear among many has been woven tightly into the fabric of terrorism discourse for decades.  

But the current century has witnessed an evolved threat paradigm in which the aim of a new type of terrorist group is to achieve “a lot of people watching and a lot of people dead”. Chemical weapons are often presented as the apex of such a goal. Yet increasingly it is argued that chemical weapons are merely a tool to elicit fear that far exceeds their actual destructive clout. This fear is a very human response. The psychological power of chemical weapons is intrinsically linked to their contaminant nature, indiscriminate harm and ability to undermine an individual’s sense of security.

Are chemical weapons really weapons of mass destruction, with a devastating impact on infrastructure, life, and property? Or, are they weapons of terror? Distinguishing between the two, this article queries how uncertainty feeds the fears surrounding chemical weapons. To what extent does the weapon of terror moniker depend on the concept of mass destruction?

The enduring power of contamination

Chemical weapons have an ancient history. Early hunter-gatherers learned to poison their arrows to ensure an effective kill. Poison gas as a weapon of war was recorded by Thucydides in 428 BCE. The scorched earth tactic of poisoning wells using the rotten corpses of people who had died from infectious disease was used across the Ottoman era and Middle Ages. Chemical weapons have been utilised – or attempted – in many conflicts since then. The British government, for example, approved the use of sulphur fumes at the siege of Sebastopol during the Crimean War. Even in Afghanistan and Iraq, the US Army used white phosphorous grenades, as did the British.

As scientific advances began to allow a greater multiplicity of chemical agents in industrial quantities, concerns mounted over potential consequences. In recognition of the sentiment that injury or death by poison is inhumane, the Hague Conventions (1899 & 1907) outlawed the battlefield use of poisoned weapons and toxic gas via projectiles. The declaration prohibiting the dissemination of asphyxiating and deleterious gases was ratified by all major powers except the US which refused to sign, arguing that projectiles as detailed in the convention had not yet been fully developed.

The use of poison has long been regarded as morally reprehensible. This harks back to disdain inherent to poisoning and its associations with chemical weapons: in contrast to the hero’s death by sword in battle, poisoning is regarded as cowardly and secretive. Yet this became more acute in the aftermath of the Hague Conventions: moral indignation follows the breaking of accepted conventions, shattering indoctrinated agreement as to non-use. In the early 20th century, both Allies and Axis powers were reluctant to be the first to breach the law.

Even General John Pershing, having established the U.S. military’s first gas warfare unit in 1917, denounced chemical weapons as “abhorrent to civilization…a cruel, unfair and improper use of science…fraught with the gravest danger to non-combatants”. By the end of WWI, over 124,000 tonnes of chlorine, phosgene and mustard gases had been dispersed, causing approximately 90,000 deaths and 1,230,853 injuries and earning WWI the moniker, “the chemist’s war”. Though the development of gas masks reduced the number of casualties in the later years, the scale of chemical warfare had set the precedent for a lingering psychological and moral response. That even Hitler refused to use chemical weapons on the battlefield (if not in the gas chambers) cemented their standing as a wholly unacceptable weapon of war.

For decades, the threat from chemical weapons remained largely in the hands of states. Almost two decades since the Chemical Weapons Convention came into force outlawing the production, stockpiling, and use of chemical weapons, the threat of non-state actors obtaining or producing chemical weapons has become of increasing concern. Large quantities of improperly disposed unconventional weapons have been unearthed in recent decades. After WWII, for instance, tons of mustard gas, sarin, soman, tabun, hydrogen cyanide and many other agents were left in storage facilities near towns and cities, buried in landfills across the world or dumped at sea. During the Cold War, chemical weapons facilities proliferated across the world, shrouded in secrecy. Throughout this time, in the Soviet Union thousands of tonnes of chemical materials were simply dumped in undisclosed, unchartered locations. With the collapse of the Soviet Union, some chemical research units were abandoned, leaving available a mass of untraced and unacknowledged weaponry.

Chemical weapons and non-state actors

Various terrorist organisations have spent years working on developing chemical weapons, of which the so-called Islamic State (IS) is but one. The eleventh volume of al-Qaida’s Encyclopaedia of Jihad provides instructions on how to construct chemical and biological weapons, although al-Qaida seems to have balked at actually using such weapons. Where groups have succeeded in their use, they have created vast shockwaves, with minimal outlay. In 1978, a Palestinian group injected non-lethal quantities of mercury into Jaffa oranges leading many countries to cease imports, jeopardising a market worth $172 million to Israel at the time. In 1989, terrorists reportedly laced Chilean grapes with cyanide, costing the Chilean fruit industry $333 million, despite the chemical only having been identified in two grapes.

In 1995, Aum Shinrikyo unleashed the largest gas attack in peacetime history on several lines of the Tokyo subway, killing 12 people and injuring thousands. Though the proportion of people killed was relatively low compared to numbers injured, the attack demonstrated the ability of non-state actors to obtain and use significant quantities of non-conventional weapons. It has subsequently been cast as a “crossing of the Rubicon” (to pass a point of no return), foreshadowing further similar attacks.

Chemical anxieties

Chemical weapons elicit a very specific emotive and political response. When the threat and impact of terrorist attacks using conventional weapons against Western targets is so real, why does the as-yet unrealised potential for chemical terror attacks in the West retain a particular power over our thinking?

Attempts to explain the anxieties surrounding chemical weapons remain incomplete when considered alongside conventional weapons with similarly cruel capabilities. Why, as in Aleppo or Homs, do we regard using explosives to tear people apart as more humane than burning or asphyxiating them to death? Weapons such as “soft nosed” bullets (which disintegrate upon entry to the body) were banned alongside asphyxiating gases by the 1899 Hague Conventions, yet they do not receive such global censure.

Part of the concern specifically attributed to chemical weapons lies in the human fear of unpredictable, adverse events such as the potential to develop illness after exposure. The most terrifying threats are those perceived not just as lethal but as dehumanising. The fear of chemical weapons is therefore, at least partially, a result of their potential to cause insidious harm.

So the potency of chemical weapons lies in the unknown and in how they fester in the imagination of those who have felt threatened by them. Chemical weapons attacks are distinguished by the propagation of functional somatic – medically unexplained – physical symptoms, bestowing unconventional weapons a “psychogenic” hallmark. A result of the potential for chemical weapons to yield psychiatric illness, the notion that the long-term psychological consequences of unconventional weapons may be worse than acute physical, is popular in psychological circles. The many chemical incidents in which low-risk patients far outnumbered those whose exposure could be confirmed, contribute to this “weapon of terror” epithet: the perception of exposure to a toxin is a greater determinant of health status and anxiety than actual exposure. After the Aum Shinrikyo attack, over 4,000 people with no sign of exposure sought medical care.

Many chemicals are perceived by the public as having a high to extreme degree of uncertainty; many, too, elicit strong anxiety, which can drive somatic symptoms. In order to form judgement under uncertainty, people form intuitive assessments upon relevant information. Attempting to decrease their uncertainty, people may apply preconceived beliefs (for instance, that chemicals are dangerous) to symptoms, even if benign, constructing a causal link between symptom and event.

Consider, for instance, cases in Israel, a nation so subject to the corollaries of war that it has been termed a natural station for the study of stress. During the 1991 Gulf War, Israel endured 18 Scud ballistic missile attacks from Iraq. The stress of conventional bombardment was compounded by the fear that the missiles contained nerve agents; residents had been instructed to carry gas masks and prepare for Iraqi use of biological or chemical weapons. Fearing contamination, over 1,000 patients attended medical facilities with symptoms such as tremors and breathing difficulties. Only 22% of patients had been genuinely injured: none by biochemical agents. 27% of casualties had mistakenly injected themselves with atropine, an antidote to nerve agents.


There are two schools of thought explaining the power of chemical weapons. On one hand is the argument that chemical weapons can be harnessed as weapons of mass destruction. This bears significant political pull. On the other, there is scepticism as to their capabilities, where instead they are branded weapons of psychological terror. The schism between “weapon of terror” and “weapon of mass destruction” is rarely acknowledged. Conflation of the two allowed Tony Blair to drawn upon their psychological power to justify the 2003 invasion of Iraq, which shattered the Middle East.

The truth lies somewhere in between. The psychological and physical fallout of chemical weapons are, essentially, two sides of the same coin. Feared or sustained physical harm gives rise to short-term anxiety and long-term psychological distress. Chemical weapons victims may never be definitively free from the physical effect, thus the psychological effects may endure. Uncertainty directly impacts upon fear, and is thus one of the most influential features of human history. As human experience is a complex nexus of affect, behaviour, cognition and physiology, chemical weapons are disturbing for their ability to bear upon each, fracturing this integration. Uncertainty can become visceral. While war does not accommodate certainty, the potential use of chemical weapons will feed doubt and continue to draw substantial political influence.

Clare Henley divides her time between acting as Assistant to the Director of the Oxford Process, and as Project Officer at Refugee Trauma Initiative. She previously worked on the Humanitarian Impact of Nuclear Weapons Initiative at Chatham House, and at the Maudsley Hospital’s Centre for Anxiety Disorders and Trauma. Prior to this, she interned on a decontamination project with the Behavioural Science team at Porton Down, Public Health England. Clare has an MSc in War and Psychiatry from King’s College London, where her thesis focused on the psychological impact of chemical, biological, radiological and nuclear weapons. Her other work focused on topics such as the impact of war on child soldiers and of being held hostage. She also has a BSc in Psychology from the University of Exeter.