*I recently wrote this analysis for Global Intelligence Trust and decided to repost it here.

Sam Seitz

With the recent terrorist attacks in Europe and the Middle East, the threat of terrorism has reclaimed the headlines. Massive refugee flows and fearmongering politicians have only further exacerbated concerns over the risk of terrorist attacks. Unfortunately, it seems likely that lone-wolf attacks and strikes from well-organized terror cells will continue to plague Western democracies. It is simply too challenging to find and stop every potential extremist from executing his or her plan. Fortunately, the risk of conventional terrorism in absolute terms is still quite low. There is a far more terrifying threat, however: the risk of WMD terrorism. Using nuclear, biological, and chemical (NBC) weapons, terrorist networks could execute mass-casualty attacks that devastate entire cities. At least that is what certain pundits would have you believe. This report is more sanguine, though. Thoroughly examining the risks of NBC attacks, this report finds the threat of WMD terrorism to be vanishingly small.

Of all the potential WMD terror attacks, nuclear attacks seem to generate the most fear among the public. This is not surprising. After all, nuclear weapons represent the pinnacle of humans’ destructive potential, and Hollywood frequently utilizes nuclear weapons to drive the plot in movies ranging from Dr. Strangelove to The Avengers. Fortunately, though, there is very little risk of terrorists acquiring or detonating nuclear weapons, particularly in large, Western metropolises. The reason for this is simple; it is exceedingly difficult for terrorists to acquire and transport nuclear weapons without being detected and stopped. First, terrorists would have to break into heavily guarded facilities, likely in Russia or the United States, and steal weapons weighing multiple tons. Then, after securing the weapons, these terrorists would need to escape while being pursued by elite security forces. Assuming the terrorists are able to escape, they would then need highly skilled technicians to assemble the nuclear device, as nuclear weapons held in storage are almost always broken down into their constituent parts so as to prevent unauthorized use. The terrorists would have to do this while being sought after by the most powerful and well-funded intelligence networks in the world, and would then need to transport the nuclear device into a major city without being detected. According to John Mueller, an expert on nuclear terrorism at Ohio State University, the risk of a successful nuclear terrorist attack occurring is, therefore, less than one in three billion (1).

Certain analysts contend that while the risk of terrorists stealing nuclear weapons is low, it is possible that terrorists might simply construct their own nuclear devices instead. This scenario is even less likely than nuclear theft, though, as the production of nuclear weapons is an exceedingly complicated task. Terrorists would need highly specific blueprints detailing how to construct a nuclear device, access to highly enriched uranium or plutonium, and a secure, well-equipped site to construct the weapon. As Mueller points out, the odds of all of these conditions being met are quite low. Moreover, the need for so many complex and uncommon materials – highly enriched uranium, heavy industrial equipment, etc. – would raise suspicion among intelligence analysts, increasing the chance of detection. Even if intelligence agencies missed these clues one of the many middle-men used to acquire these materials might inform on the terrorist network, either for profit or because of moral qualms (1).

Some still argue that, in spite of the challenges associated with the stealing and constructing of nuclear weapons, terrorists could acquire nuclear weapons via rogue states. Essentially, the argument goes that fearing the repercussions of launching a nuclear attack, nefarious regimes like Iran or North Korea might give nuclear weapons to terrorist networks in order to target enemies while maintaining deniability. This is almost as unbelievable as the previous two scenarios, however, for a number of reasons. First, as John Mearsheimer argues, states likely wouldn’t hand over such expensive and complex weapons to unreliable terror organizations because it is entirely possible that those organizations would choose to use the weapon against a target not approved by the patron state. Furthermore, there are very large risks associated with abetting nuclear terrorism. If other countries were to ascertain which state provided the nuclear weapon, there would be severe consequences imposed on the patron state ranging from comprehensive economic sanctions to a nuclear strike (2). Indeed, a comprehensive study by Keir Lieber and Daryl Press suggests that the U.S. would almost certainly be able to trace the nuclear weapon back to where it was produced by utilizing isotope tracing. Thus, rogue states derive no benefits from providing terror networks with nuclear weapons because their culpability would be immediately clear, therefore eliminating the only advantage of using terrorist groups: deniability (3).

Of course, a nuclear warhead is not the only way in which radioactive material can be used to inflict casualties. Terrorists groups could also utilize a “dirty bomb,” a weapon that uses radioactive dust and debris to cause illness and suffering. Dirty bombs are far easier to construct, as there is no need to develop complex detonation mechanisms used to trigger a nuclear chain reaction. Terror groups would simply need to acquire a large conventional bomb and pack it with radioactive material so as to distribute radioactive particles during the explosion. While certainly simpler than nuclear warheads, the production of dirty bombs still requires access to radioactive material, presenting terrorist groups with many of the same problems associated with building a nuclear bomb. Dirty bombs are also far less lethal than nuclear weapons: The radioactive powder used to cause damage would likely only spread a few blocks at worst (4). The limited effects of dirty bombs thus make the high costs and hazards associated with their construction even more acute, as the high risks would only generate limited payoffs. In sum, it is simply not plausible that terrorists would be able to acquire high-yield nuclear weapons, and it’s unlikely that terrorists would take enormous risks simply to detonate a largely ineffective dirty bomb.

Of course, nuclear weapons are not the only WMD system. Chemical and biological weapons also seemingly pose serious threats to public safety, especially when they fall into the hands of terrorists. However, when one begins to examine the risks of chemical or biological weapons, one finds that chemical and biological weapons are far less concerning than they originally appear. Chemical weapons are unlikely to pose a serious threat for two reasons. First, they are banned under international law, thus making acquisition of potent compounds challenging. Second, there are no empirical examples of successful chemical attacks. Indeed, when the Aum Shinrikyo cult did initiate a large-scale chemical attack in Tokyo in 1995, it produced only minimal casualties (5). The problem with chemical attacks is that it is incredibly challenging to effectively engineer compounds in a way that maximizes lethality while also ensuring that the agent does not dissipate before affecting large numbers of victims (6). Therefore, it is unlikely that terrorist organizations would dedicate time and resources to the development of chemical weapons. They are simply too fickle.

Biological attacks are equally unlikely to occur for many of the same reasons. There simply aren’t many biological weapons programs because the use of these kinds of systems is prohibited by international law. Thus, few individuals have the requisite knowledge to engineer and produce effective bio-agents. Without proper expertise and infrastructure, it is unlikely that terrorist networks will ever possess the knowledge or means to produce weapons grade biological agents (7). Like chemical weapons, biological weapons also have a poor track record when it comes to inflicting serious damage. As Alan Dove explains, “Terrorist groups have… deployed biological weapons twice… The first was [in] 1984… [when] a cult in Oregon inoculated restaurant salad bars with Salmonella… 751 people got sick, but nobody died.” The second biological terrorist attack was conducted by another cult, the same one that launched the chemical attack in Tokyo; its bio-attack was even less effective than its chemical attack. Despite the cult being “well-financed, and [having] many highly educated members… Nobody got sick or died” (8). Finally, it’s important to remember that the United States and other Western countries have impressively modern and well-funded public health institutions. Thus, even if terrorists are able to execute a potent biological attack against metropolitan areas in North America or Europe, it is unlikely that casualties would be high, as well-stocked hospitals and emergency response units would be able to mitigate the impact and prevent worst case scenarios.

The risk of WMD terrorism is, of course, not zero. A NBC attack could occur despite the many mitigating factors, and even if it does not cause excessive casualties, the fear and paranoia it would generate could be extremely disruptive. Thus, this report is not suggesting that intelligence and public health measures designed to prevent and mitigate NBC attacks should be curtailed. Instead, this report simply seeks to remind people that the odds of an effective terrorist attack using weapons of mass destruction remain quite low. It is important to understand the relative risks of different threats in order to make informed policy decisions, and, thus, it is crucial that the threat of WMD terrorism not be overly inflated.


Works Cited

(1)- Mueller, John. “Calming Our Nuclear Jitters.” Issues 26(2) (Winter 2010).

(2)- Mearsheimer, John. “Conversations in International Relations: Interview with John J. Mearsheimer (Part II).” Sage 20(2): 231-243.

(3)- Lieber, Kier A. and Daryl Press. “Why States Won’t Give Nuclear Weapons to Terrorists.” International Security 38(1) (Summer 2013): 80-104.

(4)- Mauroni, Al. “Don’t Fear the Dirty Bomb.” War on the Rocks. October 16, 2015. Web.

(5)- Easterbrook, Gregg. “The Smart Way to be Scared.” Homeland Security. February 16, 2003. Web.

(6)- Smithson, Amy E. “Frequently Asked Questions: Likelihood of Terrorists Acquiring and Using Chemical or Biological Weapons.” Stimson Center. 2002. Web.

(7)-  Ben Ouagrham-Gormley, Sonia. “Barriers to Bioweapons: Intangible Obstacles to Proliferation.” International Security 36(4) (Spring 2012): 80-114.

(8)- Dove, Alan. “Who’s Afraid of the Big, Bad Bioterrorist?Alan Dove. January 24, 2012. Web.