ISIS Cohort Transnational Travels and EU Security Gaps: Reconstructing the 2015 Paris Attack Preplanning and Outsource Strategy

We explore the underappreciated role of organizational tactics in terrorist violence in an understudied single case: ISIS’s execution of the November 13, 2015 Paris attacks. It is one of the first systemic reconstructions of the journeys made by two ISIS strike cohorts in the coordinated attacks, as teams traveled from the Levant to Europe. In contrast to other high-profile attacks, terrorism scholars have not undertaken a detailed reconstruction of this event, even while open source information is now available. By examining the transnational travels of foreign terrorist fighters, we identify ISIS’s distinctive terrorist outsourcing strategy in which operatives used their experiences to adapt to changing security conditions, while EU governments revealed limited responses. Both elements in this tightly-knit dynamic—terrorist outsourcing savvy using FTFs and EU security policy failures—were necessary to achieve this high-profile attack. The essay contributes to descriptive empirical and theoretical knowledge of terrorist tactical innovation and adaptive operational learning, as these capacities are enhanced by on-the-ground organized networks to increase organizational (versus lone-wolf) campaign success. By using a single case interdisciplinary and exploratory framework, terrorism studies can delve deeper into superficially understood phenomena to isolate concepts with future cross-case value, such as cohorts and tactical adaptation.