Understanding the Taxonomy of Foreign Fighters: a Scoping Review with a Concept Analysis

Although foreign fighters (FF) have gained significant media attention across Europe, the phenomenon itself remains largely unexplored, as evidenced by the lack of a standardized definition within the European Union. Although more commonly associated with terrorism, it has been difficult to come up with a universal definition of FF, as it has fluctuated with the nature of conflicts. In some cases, FF joined terrorist organisations, as in Syria, Iraq and Somalia, whereas in others, they joined official armies, such as the case of Ukraine since 2022, or paramilitary organisations, such as FF fighting for Russia. It is for this reason that some authors make the distinction between foreign fighters and foreign volunteers, as they have been formally involved with a governmental army. Also, some foreign individuals do not join the battlefront, but stay in the back providing military training or humanitarian assistance. While others have the motivation to make profits out of a conflict and can be considered mercenaries. By taking in consideration the different types of action that foreign people have in conflicts and given the conceptual vagueness around this phenomenon that is so frequent and comes with security concerns, this study aims to address this gap by proposing a conceptual framework to analyse and categorise different types of FF, foreign volunteers and other types, according to, for instance, their affiliations, risks and motivations. Where there is a definitional and conceptual gap there is a policy challenge that must be addressed in a preventative manner. This will have impact on the definition of policies and interventions. As such, this study is a scoping review with a concept analysis, which inspects the literature produced worldwide concerning the diverse terminology that addresses this phenomenon. Results are analysed according to motivation, antecedents, conflict, affiliation, actions developed during the conflict, and consequences. This is a pioneering study in exploring the attributes behind the different terminology used to refer to FF and aspires to become a tool for EU policy. It is expected that this study will contribute to a better informed academic and policy debate on the new shifts on the topic of FF, which is a crucial policy goal of the European Commission. Furthermore, before defining legislation or reintegration and rehabilitation initiatives for people who combat in foreign conflicts, it is necessary to understand how the literature refers to them, and their different motivations and risks. The main conclusions will be presented in an Evidence and Gap Map, to identify gaps and future research needs.