An estimated 6,000 EU citizens have left their home country to join the terrorist organisation Islamic State (IS) in battle. The Netherlands has contributed approximately 260 foreign fighters to IS since 2012. Several attacks on European ground, such as Brussels and Paris, have been carried out by foreign …

This article describes the development of foreign fighters’ preparatory modes of operation between 2000 and 2013, based on an analysis of 17 closed police investigations and 21 semi-structured interviews with police investigators, public prosecutors, and lawyers. Through the use of grounded theory methods …