While the core concepts behind these brutal methods of mass-casualty warfare can trace their roots back to ancient times, the modern manifestation of biological and chemical warfare has now grown into a potentially devastating mixture of high lethality, open accessibility and doctrinal applicability to today’s terrorist organisations. In the latest installment in his series on modern terrorism, Simon Schofield of the Human Security Centre examines the very real threat posed by a terrorist-adaptation of biological and chemical warfare methodologies. 

Chemical and biological weapons are not new. As AARC Associate Professor of Respiratory Care and Health Sciences Thomas J. Johnson notes, the word ‘toxin’ comes from the Greek ‘toxicon’, derived from ‘toxon’ the Greek word for ‘arrow’. Herodotus, a Greek historian in 400 years BC noted how the Scythians dipped their arrows in a mixture of putrefied human blood, dung, and venomous adder carcasses. This would have coated arrows in venom and the bacteria that cause tetanus and gangrene. The Assyrians are also believed to have used ergot, a hallucinogenic fungus, to poison the wells of their enemies as long ago as 600 BC.

Perhaps more surprising, it is now thought that even the use of poison gas is not a novel military concept. When the Persians besieged the Roman City of Dura-Europos in AD 256, in modern day Syria, they made the first use weaponised poison gas we have yet discovered. The Persian army, having successfully approached the walls of the city, began digging to mine under, a commonplace tactic of the era. The Romans undertook the usual response to this, which was to dig a countermine and station troops ready to butcher the underminers once they broke through. However, the Persians had set a trap. They set up a brazier of burning sulphur crystals and bitumen, and used bellows to pump lethal fumes into the Roman tunnels ‘until the screaming had stopped’.

Whilst the concepts of biological and chemical weapons are thousands of years old, there are a number of factors which make biological and chemical terrorism particularly terrifying in modern times. Firstly, there has been a significant shift in terrorist ideology. Secondly, technological advances have made biological and chemical weapons much more potent, lethal, and communicable. Thirdly, due to the declining role of the state, and commodification of WMDs, these weapons are more readily available to non-state actors. Finally, globalisation, demographic shift and other social changes make global populations much more vulnerable to such attacks.

Terrorist ideology and methodology

As discussed in one of my previous articles, there is an ongoing shift in terrorist methodology. Largely, terrorist objectives towards the end of the 20th Century involved nationalist groups seeking independence from their parent state, such as the IRA pursuing Irish Unification and independence from the United Kingdom, and ETA’s campaign for an independent Basque country within Spain. There were also Cold War era revolutionary groups seeking radical political change, such as the Marxist-Leninist Revolutionary Armed Forces of Colombia (FARC), and the Peruvian Shining Path organisation. What both of these strains of terrorism had in common is that they were seeking to establish legitimate dominion over a particular population. Excessive violence in the pursuit of an objective of this kind is undesirable because it is likely to inflame the population one is attempting to rule.

However, due to what is often referred to as the religious resurgence, there is a trend towards increasing religiosity globally that is bleeding into politics. This is manifesting itself in two clear forms. Firstly, in an increase in religious fundamentalism; the belief that law comes from God rather than the State, and that violence may legitimately be directed against populations following the ‘wrong’ beliefs in order to achieve religious purity. Secondly, in the increasing prevalence of doomsday cults, which believe that the end of the world is nigh and sometimes require rituals involving mass murder and/or suicide to fulfil a prophecy or similar divine edict.

Religious fundamentalism is currently felt most acutely in the Islamic world, with groups like Islamic State, al Qaeda, and the Taliban routinely conducting religiously motivated attacks on civilian populations.  Nevertheless there are also Christian fundamentalist groups like the Lords Resistance Army (LRA) in Central Africa, Hindu extremist groups such as Rashtriya Swayamsevak Sangh (RSS) in India, Buddhist fanatics such as the Burmese 969 Movement, and Jewish zealots such as the Lehava settler organisation in Israel, as well as terrorist groups affiliated to or based in most other world religions.

Doomsday-type cults are best described by examining the Japanese Aum Shinrikyo cult, now known as Aleph. Founded by Shoko Asahara in 1984, the organisation taught that Asahara was a Christ figure, that the United States would bring on ‘nuclear armageddon’ by instigating World War 3, and that only by joining Aum and helping bring about this world-ending scenario could humanity return to a time of spiritual purity¹.  It attempted to carry out a bioterrorist attack in 1993 in Kameido, Japan, by releasing anthrax spores in aerosolised form from the roof of an eight-storey building. The attack failed because the group released a vaccine strain of anthrax, which lacked the genes necessary to trigger a symptomatic response. They also carried out a chemical attack in 1995, coordinating the release of Sarin nerve gas on three lines of the Tokyo Subway, killing 12 and potentially injuring over 5,000.

Pakistani Brigadier General S.K. Malik notes in The Quranic Concept of War that ‘Terror struck into the hearts enemies is not only a means, it is the end in itself. Once a condition of terror into the opponent’s heart is obtained, hardly anything is left to be achieved. It is the point where the means and the end meet and merge. Terror is not a means of imposing decision upon the enemy, it is the decision we wish to impose upon him.”

It is clear that nationalist independence and radical political change are no longer the driving motivations behind emerging modern day terrorist groups. In pursuit of religiously-fuelled objectives, imposing a state of terror, and eliminating non-believers now make the potent lethality and macabre theatricality of biological and chemical terrorism (B/C terrorism) a much more appealing prospect for these groups.

Technological advances

Weapons have come a long way since firing dung smeared arrows and pumping burning sulphur and bitumen fumes. Chemical weapons in modern usage take many shapes and forms, and weapons that would be useful to terrorists include blister agents (such as sulphur mustard), nerve agents (such as Sarin), and asphyxiants (such as Hydrogen Cyanide).

In World War 1 chlorine gas was deployed, but rapidly replaced by the more effective mustard and phosgene gases. The Islamic State militant group is believed to have packed conventional explosives with chlorine during attacks in Iraq and Syria, although they have had little impact beyond that already achieved by the associated explosives.

The general principle of biological and chemical (B/C) weapons is the deployment of strong poisons, be they living organisms, toxins produced by living organisms, or chemicals, either naturally occurring or manufactured in a laboratory. The lethality of chemical weapons and toxins is usually best measured using the LC50, which is the concentration of agent in parts per million (ppm) required to deploy a lethal dose to 50% of an average target population.

The LC50 value for Chlorine gas, for example is estimated at 655ppm for a group of 70kg men who breathe 150 litres of air over a ten minute exposure². This figure is 79ppm for Phosgene, a choking agent also used in World War 1. These pale in comparison to nerve agents now in modern use, with Sarin having an LC50 of 1.2ppm, and VX, which has an LC50 of 0.3ppm. 10mg of VX is enough to kill a person, as recently highlighted by the assassination of North Korean exile Kim Jong-nam in Malaysia.

Even more lethal are toxins such as ricin, notoriously used by Bulgarian secret police against Georgi Markov, who was shot with a pellet laced with ricin from a modified umbrella on the streets of London in 1978. More lethal still is botulinum, the family of toxins which cause botulism and are used in botox treatments, which has attracted interest from terrorist groups such as Aum Shinrikyo and the German Red Army Faction. Ricin and botulinum have LC50 values of 3.3 parts per billion (ppb) and 0.001ppb (1 part per trillion) respectively, making them incredibly lethal.

Whilst the tetanus weaponised by the Scythians could not be passed from person to person, and could largely only enter the body through an open wound, there is now the possibility of harnessing, and even genetically engineering highly transmissible and highly lethal bioweapons. It is not common practice to measure LC50 for lethal pathogens, but there is data available for the number of organisms required to establish an infection, and known survival rates of those infected. Using these, it has been estimated that lethal pathogens have a theoretical LC50 under ideal conditions 100 million times smaller than the most potent chemical weapons. This is due to the tiny size of individual pathogens (an anthrax spore is approximately 1.3µm in length), their ability to reproduce inside hosts’ bodies, and their communicability. The Marburg Variant U virus, which causes haemorrhagic fever symptoms similar to Ebola, is believed to be lethal with exposure to a single organism. According to Soviet defector Dr. Ken Alibek, the Soviet Union was in a position to mass-produce U Variant for use in MIRV delivery weapons systems as early as 1991.

Commodification of WMD

Since World War 1, individual nation states have carried out huge amounts of research and design work on B/C weapons. This has built a large bank of knowledge pertaining to the development and delivery of chemicals, pathogens, and toxins. In the new age of connectivity and emphasis on knowledge, much of this information is proliferating beyond the sealed concrete bunkers of Porton Down and Newport Depot. Now, much of the knowledge and even much of the equipment required to research and develop B/C weapons is within reach of the average PhD student in a related field, and potentially to lesser skilled individuals.

To give an example of how far biotechnology has come even in the last decade or two, look at the human genome. In 2001 it was possible to have one’s individual genome, the complete sequence of nucleotide pairings, mapped out at the astronomical cost of $95,263,072. This was not only well beyond the reach of the average individual, but obviously shows that experimenting with genetics was likely well beyond the reach of all but the most well funded terrorist movements. As of October 2015, this same service is available for $1,245 and is routinely used by private individuals across the globe. This demonstrates how increasingly accessible biogenetic technologies now are.

When put together with the fact that the complete genomes of pathogens such as the 1918 Avian Flu, which killed over 50 million people, are now available online [4], it takes very little imagination to see the potential for bioterrorism. In 2006 James Sanderson, a journalist for the Guardian was able to obtain part of the genome for smallpox by mail order, revealing this with a damning polemic against lax laws.

One scientist remarked in 2003 that ‘the advent of the home molecular biology laboratory is not far off [as] the physical infrastructure of molecular biology is becoming more sophisticated and less expensive every day. Automated commercial instrumentation handles an increasing fraction of laboratory tasks that were once the sole province of doctoral level researchers, reducing labor costs and increasing productivity. This technology is gradually moving into the broader marketplace as … any cursory tour of eBay will reveal. [This] will soon put highly capable tools in the hands of both professionals and amateurs worldwide.’ By 2009 there were was an article online with the headline ‘Using eBay to set up a molecular biology lab: costs less than $1000!’

Ongoing instability and conflict is further fuelling this trend, with widespread reports of biolabs in Syria being looted, even in areas held by al Qaeda affiliate Jabhat al Nusra. There is a specific concern around Yazid Sufaat, a US educated biochemist known to be attempting to procure anthrax for al Qaeda; being active with Jemaah Islamiyah and Tanzim al Qaeda Malaysia, al Qaeda’s Malaysian affiliate and a splinter group thereof. Sufaat was believed to be attempting to establish a Malaysian network in Syria, at a time when the nation’s biolabs were being looted. Sufaat was detained in 2013 in Malaysia and charged with promoting terrorism in Syria. After protracted legal proceedings Sufaat plead guilty to a lesser charge of omitting information relating to terrorist acts and was sentenced in 2016 to seven years in prison, dating from his original detention in February 2013, this suggests that he will be released as early as 2020. Whilst it is important to note that Sufaat continues to protest his innocence, the evidence against him is strong, having been named specifically by 9/11 architect Khalid Sheikh Mohammad. Perturbing questions remain as to exactly the extent to which the Malaysian network was established, whether there was a bioterrorism angle to it, or whether it was purely for infiltrating Malaysian foreign fighters, and if the former is true, how successful it has been.

Another instructive example of the dangers of bioterrorism are the 2001 anthrax attacks in the USA. Here, letters laced with the Ames strain of anthrax were sent to two Democratic Senators, an NBC News anchor, and media offices in New York and Florida. This resulted in the killing of 5 and infection of 17 others. No culprit has ever been conclusively identified, despite the FBI asserting their belief that Fort Detrick scientist Bruce Ivins was responsible. There has been some speculation that the anthrax originated from an undisclosed al Qaeda biolab based outside the US, in which traces of b. anthracis Ames were found. The inconclusive investigation was described as ‘one of the largest and most complex in the history of law enforcement’, demonstrating the difficulty law enforcement would likely have in investigating any future attacks.

This introduces the worrying concept of ‘reload’. Coined by former US Secretary of the Navy Richard Danzig, the term ‘reload’ refers to the ease with which bioterror attacks can be repeated. Danzig noted that:

‘After inflicting a national trauma on 9/ 11, the attackers could not promptly repeat their achievement. They had consumed resources that were difficult to replenish (trained pilots willing to sacrifice themselves). Even more significantly, the modality that they used depended, in some measure, on surprise … the national security vulnerabilities made apparent by [the anthrax attacks] are greater than those associated with 9/ 11. This is because of reload. Attackers who use biological weapons probably can avoid prompt detection and stockpile or replenish resources that permit repeated attack … absent exceptional luck, [we do not have] effective means of interdicting a biological attack, even if we know that one has already occurred and that others are on the way.’


As the human population has exploded, it has found itself increasingly vulnerable to a mass casualty chemical or biological attack, particularly in Asia, where more than half of the world’s population now lives. It goes without saying if one releases the same amount of chemical or biological agent in a densely populated area as a sparsely populated area, that, all other things being equal, far more people would be harmed in the former. This effect is further magnified in the case of transmissible weaponised pathogens, as the greater number of infectees spread the disease more widely and more rapidly.

Improved global connectivity further magnifies the problem in two important ways. Firstly, as with all transnational terror attacks, the ease with which one can travel and communicate between countries allows an attack to be planned in one place, prepared in a second, and carried out in a third, using planners, financiers, scientists and operatives from any number of countries. This offers access to a wider pool of expertise, a larger number of vulnerable people to radicalise to carry out attacks, and confounds law enforcement by crossing national boundaries. Secondly, once released, communicable pathogens are unleashed not only to a single country, but to the entire globe. An illuminating example of how such a disease could spread is the SARS outbreak of 2002-2003. The first case was reported in Guangdong province, China, where a farmer died after being admitted to the people’s hospital of Foshan. Shortly thereafter, the disease appeared to have spread to healthcare workers and family members. From there the disease spread to Hong Kong, where the majority of fatalities and infections were reported. However, as Hong Kong is an important global business hub it did not take long for the disease to make it overseas and by the time it was brought under control there had been a reported 8,096 cases, including 774 fatalities, in 28 countries.

Since 2003 the world has gotten smaller. Transport links are cheaper to access and more plentiful, and the potential for a massive outbreak, either naturally occurring or as a result of bioterrorism, has only increased, as has been demonstrated with subsequent outbreaks such as MERS and Ebola.

It is not only developing countries which are at risk either, a report published in October 2015 concluded that the United States was ‘far more vulnerable to bioterrorism attacks’ that it needed to be. The report further uncovered areas of lax security and poor procedures, and noted that the US as a country was lacking a coherent centralised biodefence system. Perhaps most worrying of all were the comments that by funding billions of dollars’ worth of research into bioterrorism, the US, in massively increasing its demand for bioscientists had inadvertently proliferated dangerous knowledge in the field to a larger number of people, potentially increasing the risk of such knowledge being used by adversaries.


The world could well be walking into a perfect storm which could result in mass exposure to harmful substances, or even an outbreak of a lethal pathogen. Terrorist groups are more motivated than ever to make use of weapons of mass destruction, with shifting priorities and objectives more oriented around inflicting mass casualties. Technology has advanced to the point where a nerve agent can kill with a single drop of liquid and toxins are lethal at one part per trillion.

Extremists now have potential access to the knowledge, the technology, and the raw materials required to perpetrate a mass casualty chemical or biological attack and, due to the concept of reload could carry out repeat attacks and relatively lower cost than the initial attack. At the same time the global population is more vulnerable than ever, with populations denser than ever, more connected than ever and further travelling than ever.

The world could soon become a plagues’ playground.

Simon Schofield is a Senior Fellow and Acting Director at the Human Security Centre, where he researches a broad range of security issues from terrorism, weapons of mass destruction and human rights issues. He has served as a geopolitical consultant for numerous news outlets including the BBC, RTE, and the International Business Times.

Photo credit: United States Government


[1] Lifton, Robert Jay (2000) Destroying the World to Save It: Aum Shinrikyo, Apocalyptic Violence, and the New Global Terrorism. New York: Macmillan

[2] Maurer, Stephen M (2009) ‘Technologies of Evil: Chemical, Biological, Radiological, and Nuclear Weapons’, in Maurer, Stephen M (ed.) (2009) WMD Terrorism: Science and Policy Choices, Cambridge, MA: MIT Press.

[3] ibid

[4] Bobbit, Philip (2010) Terror and Consent: The Wars for the Twenty-First Century,


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