This report was tendered by the National Coordinator for Counter-Terrorism and Security (NCTV) and commissioned by the Research and Documentary Centre of the Dutch Ministry of Security and Justice. The report’s authors want to thank the members of the supervisory board for the time and effort that they spent in helping to solve the questions encountered during the research stage of this report. They include the president of the committee, Professor Ramses Wessels (University of Twente), and committee members Jos Vaessen (University of Maastricht), Hans van Miert (National Coordinator for Counter-Terrorism and Security, NCTV), Professor Jan Melissen (Netherlands Institute of International Relations ‘Clingendael’), as the replacement of Edwin Bakker, Peter Knoope (International Centre for Counter-Terrorism, ICCT), Gerry van Klinken (Royal Netherlands Institute of South-East Asian and Caribbean Studies, KITLV) and Casper van Nassau (Wetenschappelijk Onderzoeken Documentatiecentrum, WODC [Research and Documentation Centre]). The authors also thank Bibi van Ginkel (Netherlands Institute of International Relations ‘Clingendael’) for her contribution at the beginning of the project.In addition the team has been inspired by the excellent comments and remarks made by experts Camille Tawil, Beatrice de Graaff and John Sidel during a seminar on 17 June 2011 at Clingendael Institute in The Hague. We would like thank them for sharing their insights with us.