With the exception of the most technically unsophisticated and spontaneously initiated plots, planning and preparing for a terrorist attack requires time, resources, skills and knowledge. There is thus a process in which terrorists acquire the capabilities that are necessary to carry out an attack. Likewise, because people generally do not become involved in terrorism overnight, planning and preparatory activities are likely to be preceded by a period in which violence-legitimizing beliefs are internalized and socialization into an extremist or terrorist group takes place. Individuals who progress along the timeline from initial involvement in radicalism to conducting preparations for an attack are likely to express or behave themselves in ways that provide clues about their intent as well as their capabilities. Such behaviors and expressions can potentially function as ‘early warning indicators’, provided they are detected on time and interpreted correctly.

Terrorists place a premium on secrecy. It therefore seems odd that they would give off signals that could be used to judge their intent and capability to commit an attack. Yet even the most skilled terrorists are hard put to maintain complete operational security. In Terrorism as Crime, Mark Hamm shows that those responsible for the 1993 bombing of the World Trade Center were proficient in terrorist essentials such as bomb-making, but lacked criminal tradecraft, leaving them susceptible to law enforcement interdiction. Hamm also covered a group of American right-wing extremists who were highly capable a both terrorists and criminals, but who felt compelled to tell others of their exploits, thus breaching their operational security. Research by Strom and colleagues has shown that more than 80% of the terrorist plots foiled in the United States between 1999 and 2009 were discovered after law enforcement personnel or a member of the public detected suspicious activities.

These are encouraging findings, as they point to the feasibility of using early warning indicators of terrorist intent and capability to prevent attacks from taking place. Working from this foundation, my co-author Quirine Eijkman and I conducted a research project that looked at several European homegrown jihadist groups and individuals with the aim of learning more about such potential indicators. An undertaking of this kind must of course acknowledge that there is no clear or causal link between thoughts, beliefs or intent and actual behavior. Our goal was never to uncover a ‘holy grail’ of some sort that would under all circumstances reliably point towards terrorist intentions. Instead, we devised an analytical framework that represents terrorists’ pre-attack process as consisting of seven phases and we ‘populated’ that framework with indicators of intent and capability taken from in-depth case study analysis.

Hopefully, this research will be able to make a contribution to the ability to detect and disrupt terrorist plots before they can be executed and further debate on what research on potential indicators of terrorism can accomplish. Interested readers can read the full article here.