Author: Jonas Feltes


1          WMD terrorism – Risks and consequences

2          Proliferation of knowledge and its prevention

3          Proliferation of materials and its prevention

4          The attack and societal resilience


1 WMD terrorism – Risks and consequences

The threat of terrorist attacks with weapons of mass destruction (WMDs)[1] is controversially discussed among security experts, policy makers, and academics. While some researchers maintain that these weapons – and especially nuclear and biological weapons – are unlikely to be used by terrorist groups in the near future, others warn that even a low probability of WMD terrorism must be taken extraordinarily serious considering the devastating consequences that the terrorist use of these weapons might lead to. However, it is important to note that the term WMD does not refer to a homogenous concept but rather consists of a variety of different weapon technologies of which some are more likely to be used by terrorists than others. Furthermore, the anticipated consequences of some WMDs in the hands of terrorists are far more devastating than others.

According to experts like Gary Ackerman and Ryan Pereira, chemical as well as radiological devices are currently the most likely WMDs to be used by resourceful terrorist groups such as the so-called Islamic State (ISIS). This likelihood can be in parts explained by the availability of the materials and expertise that are necessary to assemble these weapons. Unlike nuclear weapons or pathogens, radiological and chemical weapons are (at least in theory) relatively easy to improvise by using openly available or only few restricted materials. These improvised devices can be roughly grouped into two types: (1) the first type simply entails the exposure of persons to a certain chemical or radiological substance. Examples for such weapons would be the sarin canisters that were opened in the Tokyo Subway by Aum Shinrikyo or (theoretically possible) hidden, unshielded radiological exposure devices (REDs). (2) The second type refers to the combination of a radiological or chemical substance with an improvised explosive device (IED) to disperse the hazardous materials. Examples of these weapons would be IEDs strapped to chlorine canisters that were used by al Qaeda (AQ) in Iraq or so-called “dirty bombs”, i.e., radiological dispersion devices (RDDs).

Although the terrorist use of improvised chemical or radiological weapons is greatly feared in public and the consequences of such attacks are publicly believed to be almost apocalyptic, both types of the above described weapons would, in fact, manage to create very limited casualties in comparison with nuclear or biological weapons. RDDs, in particular, do not seem to cause more physical damage than the detonation caused by their IEDs. However, while the physical damage caused by chemical or radiological devices might not exceed the damage caused by IEDs, the psychological consequences of such attacks could indeed by devastating – in part because the risks and consequences associated with these weapons are publicly believed to be severe. For example, radiological devices and especially “dirty bombs” are falsely believed to be small nuclear weapons. This social amplification of risks associated with radiological and chemical could in return cause terrorist groups to be more interested in these technologies: Simply because society reacts extremely fearful towards the possibility of chemical and radiological (CR) terrorism, groups like ISIL might, in fact, be more willing to invest their resources in conducting an attack with, for example, an RDD. Even if the physical damage of the attack might not exceed the damage caused by a conventional weapon, the psychological damage and publicity would benefit the group’s cause to a large degree.

Because of its potential to cause large scale disruption in societies, security agencies are taking multiple measures to counter CR terrorism. Both the threat of terrorist gaining the capability to assemble a CR weapon as well as these corresponding countermeasures to contain that threat will be the subject of the present paper. The vast majority of CR terrorism countermeasures are not specifically focused on the weapon technologies, but present more general counter-terrorism approach such as intelligence collection and analysis or the promotion of public vigilance. However, other measures specifically target attacks with advanced weapon technologies such as CR weapons. Three particularly salient groups of these measures with focus on the weapons will be discussed in this paper:

First of all, security agencies attempt to restrict the access to relevant information on how to use chemical or radiological substances as weapons. Moreover, law enforcement and policy makers attempt to restrict the access to materials and technologies that are needed to assemble these weapons. In addition to denying terrorists access to certain information and materials, Governments often choose to provide their citizens with both information and materials on how to respond to an attack with CR weapons to increase societal resilience. Resilience in this regard refers to the ability of citizens to respond to a terrorist attack in proper way and to have the necessary information at hand to prepare for the possibility of such an attack. In contrast to the two above described measures against the acquisition of knowledge and materials to assemble CR weapons, these calls for resilience are not focused on the prevention of an attack, but aim to prepare the response to it.

However, since an exhaustive discussion of all facets of these three groups of measures would certainly exceed the scope of this paper, one specific, prominent measure of every group will be selected and discussed in three short analyses. For the first group of countermeasures that is focused on preventing the acquisition of relevant knowledge by terrorist groups, the removal of online weapon manufacturing manuals shall be discussed in this study. The second group of measures, that is concerned with fighting against the proliferation of relevant materials, shall be represented by the practice of regulating and restricting the access to certain chemicals and isotopes. Finally, the third group of measures, the one focused on societal resilience, will be discussed by using the example of information materials that are distributed to the citizens to give instructions on how to respond to an attack.

2 Proliferation of knowledge and its prevention

One prominent measure to prevent terrorists from committing attacks with CR devices is to prevent them from acquiring the knowledge to assemble these weapon technologies. With the emergence of the internet, these efforts have been more and more focussing on monitoring and deleting relevant information and specifically weapon manufacturing manuals online.

Globally operating terrorist groups like AQ and ISIS have developed multiple ways to provide their members and sympathizers around the globe with the technical expertise to carry out attacks. Next to training camps in Middle Eastern countries and knowledgeable individuals (“bomb makers”) that share their expertise with operators in the West, members of these groups also produce manuals and even attempted to create online learning courses for sympathizers. For example, both ISIS and AQ publish own online magazines (Rumiyah (former Dabiq) and Inspire) with instructions on how to manufacture explosives or how to commit knife or car attacks. In addition to that, AQ operatives created an Encyclopaedia of Afghan Jihad in the 1990s that teaches members of this group in explosive manufacturing, weapon use, tactics, and also give insights into WMD manufacturing possibilities including chemical and radiological warfare.

However, it is important to note that the online materials used by AQ and ISIS operatives are not strictly professionalized manuals and publications of the group’s leadership, but rather a conglomerate of diverse contents. For example, operatives and sympathizers of both groups are known to have used a wide range of online materials that provide expertise in weapon manufacturing including CR weapons. These materials include but are not limited to publications of groups with different ideological backgrounds (such as anarchists or white supremacist groups), but also information retrieved from scientific publications and openly accessible websites.

For example, military operative and journalists found copies of the publication Assorted Nasties by David Harber in the AQ training compounds Abu Khabab in Afghanistan. This book is openly available on the internet and includes manuals on the production of hydrogen cyanide as well as instructions on how to extract ricin. Furthermore, senior AQ operatives such as Ayman al Zawahiri are known to have retrieved information on chemical warfare from “different books and articles from biomedical journals” on at least one occasion as René Pita and Arturo Anadón report. Moreover, the right-wing terrorist Anders Behring Breivik appeared to have used exclusively legal online sources to acquire and present basic knowledge on how to assemble radiological devices in his ego document 2083 – A European Declaration of Independence. In a detailed section on the possibilities of acquiring and assembling RDDs, Breivik mentions several sources that he apparently used to acquire the expertise expressed in this section. These sources include the U.S. Department of Energy, a “government security overview”, the U.S. Nuclear Regulatory Commission (NRC), press coverage of the Goiania incident in Brazil[2], and the International Atomic Energy Agency (IAEA).

However, as researchers like Anne Stenersen and Michael Kenney have repeatedly pointed out, contents like manuals or technical information on the internet might not be enough to provide potential terrorists with the necessary expertise to assemble weapons such as IEDs or chemical and radiological devices. Rather, these researchers argue that especially the bearers of experienced based CR weapon expertise (tacit knowledge) in terrorist organizations such as weapon manufacturers and veterans of the Syrian civil war as well as their operational spaces such as training camps are crucial to instruct potential terrorists in weapon manufacturing. Yet arguably as complementary to the tacit knowledge provided by knowledgeable individuals, the relevant web content may help terrorist groups to gain first insights into the theoretical side of weapon-related knowledge (explicit knowledge). Furthermore, there are cases in which lone wolf terrorists acquired the technical expertise to build weapons such as IEDs exclusively via the internet without having access to any tacit knowledge. Anders Behring Breivik would be such an example.

Because of this complementary role of the internet in sharing technical knowledge among terrorist groups, law enforcement and intelligence agencies are concentrating some of their counter-terrorism efforts on denying potential terrorists the access to relevant online content. For example, the European police agency Europol set up an Internet Referral Unit (IRU) as part of its European Counter Terrorism Centre (ECTC) in 2015. This unit is, amongst others, responsible for monitoring and removing terrorist propaganda content as well as weapon manufacturing manuals from the internet. According to its first year report, the IRU flagged and asked for the deletion of 8949 pieces of web content by European internet service providers in its first operational year alone. The national law enforcement agencies of several European member are working closely together with the IRU and contribute to the search, analysis and flagging of terrorist propaganda and attacks instructions on the internet. One example on a national level is the German Bundeskriminalamt (Federal Criminal Police Office (BKA)). According to a minor interpellation tabled by members of the German parliament, the section Polizeilicher Staatsschutz of the BKA established a point of contact with the IRU and cooperates with the unit in monitoring relevant contents. Furthermore, other states such as the United Kingdom set up own units for the flagging of web content regarding terrorist propaganda and instructional materials for attacks. As the Metropolitan police states, the UK Counter Terrorism Internet Referal Unit (CTIRU) is requesting the removal of approx. 2,000 pieces of relevant material each week.

Although there are no numbers of deleted chemical or radiological weapon manufacturing manuals available in case of the IRU and European national agencies, it can be concluded that the European Union and its member states actively attempt to prevent terrorist from, amongst others, gaining relevant expertise concerning these weapons by removing online manuals and other relevant web content. However, the absence of details concerning the deleted materials makes it hard to get any specific information on the criteria with which these agencies make recommendations to delete online manuals and other materials. Yet a careful review of the existing online sources of expertise to assemble  CR weapons in combination with more general observations of the activities of terrorists and extremists in the World Wide Web allows to formulate two distinct categories according to which security agencies might evaluate online content regarding advanced weapon technologies:

  1. The exclusive deletion of weapon manufacturing manuals that are either published by or obviously connected with terrorist groups or terrorist ideologies. These manuals show the clear intention of instructing persons to commit attacks. Examples of such content would be instructions in Inspire or Rumiyah.
  2. The deletion of all web content that gives instructions into the manufacturing of chemical and/or radiological weapons regardless of the intention behind this content. Examples of such content would include publications like Assorted Nasties, but also hobby manuals, entries in forums of weapon enthusiasts or so-called citizen scientists etc.

Criterion A seems to be almost certainly among the materials that is being filed for deletion by agencies such as Europol. Next to the fact that these kind of manuals are usually embedded in propaganda materials that are illegal in general, the instruction to build CR weapons with the obvious intention to commit violent crimes or acts of terrorism is an own criminal offence in many liberal democracies. For example, in Germany the criminal code explicitly prohibits “instructions to commit a serious, subversive crime”.[3] Arguable, however, some criterion B materials may also be among the content that is filed for deletion by security agencies. In fact, in some liberal democracies, manuals like Assorted Nasties or other manuals are illegal regardless of their intentions. An example would be the German weapon legislation that forbids the publication of instructions to assemble explosives or other lethal weapons.[4]

3 Proliferation of materials and its prevention

Once a terrorist group or a lone operator has the necessary information about a particular radiological or chemical weapon, said group or individual will attempt to acquire either the materials necessary to assemble this weapon or an off-the-shelf weapon. The latter possibility seems unlikely in Western European nations, since chemical weapon are either completely absent or in the highly guarded process of being dismantled in accordance with the Chemical Weapon Convention (CWC). Furthermore, the concept of radiological weapons exclusively refers to improvised devices – neither RDDs or REDs can be found in the arsenal of militaries.

Hence, for our case especially those materials are of interest that function as precursors for improvised chemical or radiological devices. To identify these materials it is necessary to both analyse what chemical and radiological agents terrorist groups have been interested in and what kind of materials that are available in Western Europe would be suitable for the needs of these agents. As for chemical agents, especially chlorine as well as phosphine could be interesting materials for terrorists aiming to assemble a chemical weapon, since both agents have been used as weapons by terrorist groups like ISIS in Syria and both of them are being commonly used around the world. For example, phosphine producing agents are widely used as pesticides in Europe and the United States and tends to be overlooked by security agencies. As for radiological agents a list of potential agents of interest is harder to create, since neither RDDs nor REDs have been successfully deployed by non-state actors yet.

However, certain terrorist groups have displayed a strong interest in deploying radiological weapons in the past and, in fact, managed to acquire the materials that would be necessary to assemble RDDs. For example, in 1995 Chechen rebels with Shamil Basayev as a commander buried a 13 kilogram box of the radiological element caesium 137 ((Cs)-137) in a park in Moscow to demonstrate the group’s ability to perform radiological attacks in Russia. Furthermore, Anders Behring Breivik listed, amongst others, the elements Cs-137, cobalt 60 ((Co)-60), and americium 241 ((Am)-241) as suitable candidates for RDDs. Numerous expert share his view. One of the most important reasons for the prominence of these elements among terrorists is the availability of them in liberal democracies. While Cs-137 and Co-60 are commonly used in radiation therapy and, thus, are present in many hospitals, small amounts of Am-241 can be found in smoke detectors.

Security agencies in Western European countries and in the USA are well aware of the threat that the availability of these chemical and radiological agents poses. Hence, in most Western countries the access to these substances is restricted. However, depending on the state or kind and amount of the substance, these restrictions can differ drastically. For example, the purchase, storage, and use of Cs-137 is strictly regulated in most liberal democracies including the United States and Germany. In the United States, the NRC regards Cs-137 a category 1 or 2 radiation source starting from a D-value of 1.E+02 and 1.E+00 respectively in accordance with the threshold values of the Code of Conduct on the Safety and Security of Radioactive Sources that was issued by the IAEA in 2004. Based on this classification, the NRC as a federal agency as well as its 32 Agreement States enforce multiple regulations concerning the use of category 1 and 2 Cs-137 in medical and industrial applications. For instance, blood irradiators based on 137caesium-chloride are only allowed to be operated by personnel that passed proper background checks and provided their fingerprints to be checked against databases of the Federal Bureau of Investigation (FBI). Additionally, blood irradiator units have to be secured by multiple layers of physical security including CCTV surveillance and advanced locks. To prevent unnoticed relocation or theft of materials such as Cs-137, the NRC established the National Source Tracking System (NSTS) that requires the documentation of all category 1 and 2 radiation sources with their location and their movement to other facilities.

The German government and in particular the German Bundesamt für Strahlenschutz (Federal Office for Radiation Protection) undertakes similar measures to prevent malicious agents from either purchasing or stealing Cs-137. Germany complies with the threshold values regarding high activity sealed sources (HASS) of the European regulation 2003/122/EURATOM and enforces compulsory regulations on the purchase, use, and movement of materials that surpass these thresholds such as many products containing Cs-137.[5] These regulations are based on several legislative texts including the Verordnung über den Schutz vor Schäden durch ionisierende Strahlen (Radiation Protection Ordinance) and the Gesetz über die friedliche Verwendung der Kernenergie und den Schutz gegen ihre Gefahren (Atomic Energy Act). Additionally, the Bundesamt für Strahlenschutz is conducting a variety of security and quality checks on radiation sources owned or sold by private entities. Moreover, the Bundesamt für Strahlenschutz established a central database for all highly radioactive source materials according to the EU definition, the HRQ-Register, to track these materials. Loss or theft of relevant materials will be reported to the international Incident and Trafficking Database (ITDB) of the IAEA.

However, not all radioactive substances are hold to such high security standards as Cs-137. For example, some products that contain radiological substances are available without restriction in liberal democracies, since these substances are only present in very small amounts in these products: In the USA one can still purchase Am-241 containing smoke detectors without any restrictions. While the amount of Am-241 present in one smoke detector is by far too little to be used as an agent for an RDD, some terrorists seem to be interested in this material and suggest that the collection of hundreds of these smoke detectors could – albeit only in combination with other radioactive materials – generate a substantial amount of radiological material to deploy an RDD. However, it is important to note that the extraction of  Am-241 as sole source of radiation would not be feasible for terrorists with the ambition to assemble a powerful RDD. According to some researchers, a group or lone operator would have to collect around 16 million smoke detectors to acquire the necessary amount to kill or substantially harm a large number of people by means of radioactive contamination. However, these researchers only consider the physical impact of such a device. Even a more or less harmless, but measurable radiological contamination of the site of the attack could have the desired psychological effect for terrorists.

The restrictions and regulations concerning relevant chemical materials in liberal democracies are even more diverse than in case of products containing radiological materials. Here, especially the case of phosphine producing pesticides is an interesting example: In the United States all products that produce phosphine after being mixed with water or acids including those products containing aluminium phosphide, magnesium phosphide, and zinc phosphide as well as all products directly containing phosphine gas (such as ECO2FUME) are labelled restricted use pesticides (RUP) by the federal Environmental Protection Agency (EPA). This means that the purchase and use of all of these products is bound to a licensing process.

In Germany phosphine producing pesticides including primarily those products containing calcium phosphide are considered Gefahrstoffe (hazardous substances) by the federal Chemikalien-Verbotsverordnung (Chemicals Prohibition Ordinance). However, according to this ordinance the purchase of certain, small amounts of phosphine producing products is solely regulated by the vendors of these products. In particular, the vendor of these products is obligated to inform the purchaser about the dangers of the substances, has to verify the Identification documents of the purchaser to make sure that the person is over the age of 18 years, and has to judge if the purchaser is both knowledgeable and trustworthy enough to handle the product in a proper way.


4 The attack and societal resilience

Once a terrorist group has acquired the knowledge and technology to assemble a CR weapon, security agencies have to assume that an attack with such a weapon might, in fact, take place. As seen in the first chapter of the present paper, attacks with CR weapons are expected to generate high degrees of fear and psychological disruption in societies rather than inflicting mass casualties. This psychological impact is amplified by a society that is uninformed about the nature and risks associated with these weapons. Hence, because of the (believed) contamination of persons and places, panic and uncertainty is likely to spread in the aftermath of such an attack. These outcomes will almost certainly increase the political as well as economic impact of an attack as well. Additionally, medical facilities might be overburdened with the psychological impact of these attacks as well: For example, in the aftermath of the Tokyo Subway attack, large numbers of Tokyo’s citizens sought unnecessary medical attention, since they did not have any information about the nature and effects of the sarin gas that was used during the attack.

Because of this threat, security agencies are cooperating with national and international crisis management institutions to create scenario-based simulations on how to respond to CR terrorist attacks. However, since terrorist attacks have, just like natural disasters, local impacts in most cases (e.g. a music festival in a small town in Germany), a national response strategy with the respective resources might not be in place soon enough to respond to a chemical or radiological attack effectively. Thus, local fire departments, regional crisis managers, and the local police forces are crucial components in the response to these attacks. In addition to these groups of actors, many governments of liberal democratic societies encourage all of their citizens to inform themselves about the threat of terrorist attacks and to undertake certain measures to prepare for these attacks in order to be able to respond to these incidents. In practice, these measures usually include information materials like leaflets, videos or presentations that present short facts about the nature of the threat and possible strategies to stay safe during and immediately after an attack. By educating the public about the threat of CR terrorism, security agencies and Governments hope to reduce the psychological impact of an attack and by suggesting ways to respond to attacks, counter-terrorism agencies aim at reducing the physical impact (i.e., the number of casualties) during an attack. In sum, the reduction of these impacts aim at increasing societal resilience against an attack with CR weapons.

Examples for this resilience strategy can be found in nearly every liberal democracy including the United States of America and Germany. The US Department of Homeland Security (DHS), for instance, published a detailed description of the nature and prospective impact of a radiological attack on its website. In this factsheet, the DHS also provides strategies to minimize exposure after an attack with an RDD. A similar factsheet can be found on the website of the NRC. Here, the NRC is not only providing information about the nature of the threat, but also gives clear instructions on how to react to an attack. For example, the NRC recommends to “[s]tay away from any obvious plume or dust cloud” and to “cover your mouth and nose with a tissue, filter, clothing or damp cloth to avoid inhaling or ingesting radioactive material”. In addition to these factsheets on radiological threats, the DHS also published a similar leaflet for chemical attacks. Here, the DHS gives detailed information on the most prevalent chemical warfare agents (yet not on phosphine) and give instructions such as “[d]o whatever it takes to find clean air quickly: exit the building if they do so without passing through the contaminated area or break a window to access clean air”.

In Germany the main source for information and instructional materials as resilience measure is the website of the German Bundesamt für Bevölkerungsschutz und Katastrophenhilfe (BBK). Here, the agency informs with an online leaflet about so-called exceptional situations of danger that include terrorist attacks with CBRN agents in general. While not specifically providing strategies to react to an RDD or a chemical device, the leaflet and the website describes the nature of different agents and gives more general recommendations in case of CBRN incidents such as removing contaminated clothing and following radio announcements closely. Furthermore, the BBK published a factsheet that is focused on chemical warfare agents in particular. Like the more general leaflets, this factsheet also includes recommendations on how to detect and respond to a chemical attack. For example, the factsheets presents the observation of large amounts of dead mammals and birds as well as the absence of insects as one way to detect a chemical attack. Furthermore, the BBK urges citizens in this leaflet to move inside in case of chemical attack and to seal all windows and doors with plastics and duct tape. Moreover, it is recommended to move upstairs in buildings, since most chemical warfare agents are thicker and, thus, heavier than air.

In addition to the leaflets and factsheets specifically focused on attacks with CR weapons, both the US and German governments have been publishing numerous, more general, informative and instructive materials to prepare their citizens for disaster situations in general – including but not specifically focused on terrorist attacks. For example, the website informs US citizens about strategies to respond to disaster situations and encourages everyone to prepare for these situations by means of storing drinking water, food, and other essential supplies at home. Furthermore, the website suggests to plan evacuation routes in advance, secure important documents, ensure communication and information sources, and to prepare specific disaster supply kits. For the special case of chemical emergencies, recommends to prepare a supply kit consisting of scissors, duct tape, and plastic bags. A similar approach has been followed by the German government. German citizens can find a detailed leaflet on the website of the BBK that encourages every German citizen to lay in a stock of essential goods in order to prepare for disasters such as floods and storms, but also for attacks on critical infrastructure or high profile terrorist attacks. This leaflet was widely advertised on German national television in July 2016 and has been controversially discussed in the German public, since its publication followed two terrorist attacks on German soil and, thereby, unintentionally fuelled worry and fear in the German society.

[1] The umbrella term WMD usually refers to chemical, biological, radiological, and nuclear (CBRN) weapon technologies.

[2] During this incidents, people in the Brazilian city of Goiania were exposed to Caesium-137 that originated from abandoned medical facilities.

[3] See StGB § 91.

[4] See WaffG § 40 Abs. 1.

[5] Although having competed with the D-value system of the IAEA, the threshold values of the European Union were harmonized with the IAEA threshold values in Directive 2013/59/Euratom.