If you were to ask a security official in most parts of the world what he or she thinks is the most pressing transnational security issue of our time, you can bet your bottom dollar on the answer to be “foreign fighters”. To quote Giles de Kerchove – EU’s Counterterrorism Coordinator – in a November 2014 Report on the Implementation of the Counter-Terrorism Strategy: “The foreign fighters issue has been the top priority in CT for the past 18 months”. Fortunately, policy makers have not been sitting on their hands. In fact, various actors have designed and implemented a whole range of policies. These policies do not merely focus on stopping potential foreign fighters but also aim to limit the possible threat posed by returning fighters that seem to be the greatest worry.

As with many rapidly developing phenomenons, there is often not much time nor the possibility to engage in thorough policy evaluations. It is only with hindsight that we can truly see whether the desired effect has been attained. This does not mean that critically investigating current policies is in vain. Something that can be done with regard to current policy-making on foreign fighters is to try to discern possible unintended consequences of these policies on the pathways foreign fighters could take.

In a recently published Policy Brief by the International Centre for Counter-Terrorism, this is exactly what has been attempted. Four policies that are currently widely applied - reintegration programmes, prosecution of returning foreign fighters, revoking nationality of foreign fighters and finally, military interventions against foreign fighters - are investigated in light of these possible (un)intended consequences on the pathways foreign fighters could take once they have arrived in Syria or Iraq.

The article concludes that each of these policy options has a wide variety of (un)intended side effects. Awareness of these possible unwanted and unintended consequences could help policymakers to weigh costs and benefits of certain approaches and to determine the best policy options. The main point of this Policy Brief is that policymakers should also take into account the indirect and long term side effects of their policies, as some may lead to a displacement effect leading to more trouble. Worst case scenario, some policy measures might provide a breeding ground for a new generation of foreign fighters.

By using the concept of pathways, the authors hope to provide a valuable framework for policymakers to identify preferred outcomes and to subsequently select those policies that help to deliver these desired objectives, whilst limiting or mitigating their possible negative side effects and, of equal importance, by preventing the most undesirable outcomes. When dealing with security concerns, especially those that we call "top priority", only looking at the direct effects is not enough.