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Wednesday, March 9, 2016

The Complex Nature of Countering Terrorism: Detection

In recent posts ("On the Complex Nature of Countering Terrorism" "The Complex Nature of Countering Terrorism: Prevention") I've argued that counter terrorism is a complex task that requires  a multipronged approach, one that involves adopting (1) measures that lower the probability that groups will radicalize, (2) methods that help detect those that have already radicalized, and (3) strategies that can disrupt groups that have already carried out attacks or are planning to.

In this post I take up the second item, namely, the problem of detection. Detecting clandestine groups can prove elusive. If they wish to remain undetected, for the most part, they can. One reason is because, like most social groups, they tend to recruit through preexisting friendship and kinship ties. For instance, Marc Sageman (2004), in his study of terrorist groups, found that 83 percent of those who joined had to tie to either a relative or friend in the group. Similarly, a recent study of 474 foreign fighters from 25 Western countries found “over a third… have a familial connection to jihad, whether through relatives currently fighting in Syria or Iraq, marriage, or some other link to jihadists from prior conflicts or terrorist attacks” (Bergen, Schuster, and Sterman 2015:8). As Mohammed Hafez (2016:13) notes,
Recruitment [is] localized and highly personal tasks involving interpersonal ties, bonds of solidarity, and trust. This is especially the case in Western societies (and strong states in general) where vigilant security services are on the lookout for overt political and religious networks seeking to radicalize and recruit others for violent ends. In a highly constricted security environment, radicals must look for recruits within preexisting networks such as educational and faith-based institutions, community centers, bookstores, religious study groups, sports teams, workplaces, professional associations, social movement organizations, local charities, and prisons. As these spaces come under the watchful eyes of the authorities, radicalizers turn to an even more secure source of recruits—the family.
Because potential threats can be difficult to detect, it could be “useful to use an approach that provides alternative images” of potential attackers; this would provide an “analytic framework” that allow us to “construct and assess well-hedged defensive strategies, even when uncertainty about the attacker’s identity persists” (Arquilla and Ronfeldt 1996:96).

Nevertheless, it is likely that once terrorist groups begin to mobilize for attacks, they will leave traces of their activities. The key, of course, is to employ methods that will detect them. Thankfully, there is some progress in this area. For example, recently developed “geographical profiling” software can help identify which areas should be searched or put under surveillance (The Economist 2016). Analysts feed the software with information about leafleting, graffiti, muggings and bombings (since terrorists often finance their cause from the proceeds of such crime), and even income distribution (because the poorer an area, the more likely there is an apartment in which people paid to store weapons).

Such an approach is akin to how the Allies used a Bayesian approach, a statistical method that begins with a priori assumptions that are repeatedly updated with new information, to locate German U-boats during World War II. The Allies had built several high-frequency direction-finding stations along the perimeter of the Atlantic. If six or seven of them intercepted the same message from a particular U-boat, they could locate the boat within a circle 236 miles across. As such, analysts initially assigned 50% probability that a U-boat was inside the 236-mile circle and then would update this probability as new data (e.g., additional intercepted messages) came to light, systematically narrowing down likely U-boat locations (McGrayne 2011:80).

A complicating factor is separating the wheat from the chaff, that is, distinguishing genuine threats from spurious ones. For instance, German authorities began tracking members of 9/11 Hamburg cell as early as 1998 and, in fact, had inserted a microphone in the apartment and occasionally monitored their conversations (Sageman 2004). That is how we know that their discussions “became increasingly virulent” and talk about defeating “world-Jewry” and the United States “through jihad… became more prominent over time” (Sageman 2004:106). However, they did not believe there was enough evidence warranting intervention (Butler 2003). This side of 9/11 it is easy to criticize them for missing evidence that could have prevented the attacks, but what it probably points to is how difficult it is to separate good intelligence from bad.

Of course, regardless of the methods employed, some groups will slip under the radar, and we will only become aware of them after an attack occurs. Thus, we must take steps to protect ourselves from future attacks:
Practically, however, absent outstanding intelligence about enemy intentions, detection will more likely occur only after an attack has begun. With this in mind, protection will become a key operational task… Damage limitation will be a primary goal and may be pursued through efforts at preclusive security (Arquilla and Ronfeldt 1996:).
To summarize, then, the detection clandestine groups is difficult. If groups wish to remain undetected, they can, at least for the most part. However, once they begin to mobilize for attacks, it is likely that the will leave traces of their activities. Thus, it is incumbent on authorities to employ methods that will detect them. Progress is being made in this area, but there remains the difficulty of distinguishing traces worth following from ones worth abandoning. Because it is impossible to detect all clandestine groups before they attack, we must take steps to protect ourselves. Regardless of how terrorist groups come to our attention, we must take steps to disrupt them. It is to that topic that we now turn.


Arquilla, John, and David Ronfeldt. 1996. The Advent of Netwar. Santa Monica, CA: RAND.

Bergen, Peter, Courtney Schuster, and David Sterman. 2015. "ISIS in the West: The New Faces of Extremism." New America (November):1-29.

Butler, Desmond. 2003. "Germans Were Tracking Sept. 11 Conspirators as Early as 1998, Documents Disclose." New York Times, (January 18). Accessed at:

Hafez, Mohammed M. 2016. "The Ties that Bind: How Terrorists Exploit Family Bonds." CTC Sentinel, February:12-14.

McGrayne, Sharon B. 2011. The Theory That Would Not Die: How Bayes' Rule Cracked the Enigma Code, Hunted Down Russian Submarines, and Emerged Triumphant from Two Centuries of Controversy. New Haven, CT: Yale University Press.

Sageman, Marc. 2004. Understanding Terror Networks. Philadelphia, PA: University of Pennsylvania Press.

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