Abstract
Why do some non-state armed groups (NSAG) in multiparty civil wars form collaborative interactions with each other while others do not? This paper argues that to understand the conditions of such interactions, closer attention needs to be paid to the question of how such NSAGs interact with one another. Previous research, which focuses on either conflict or cooperation among NSAGs, typically treats these processes as separate and binary phenomena and thus offers only partial explanations. In contrast, the paper proposes a novel framework that conceptualizes NSAG interaction on a single continuum, drawing insights from various research clusters such as terrorist cooperation and state-militia relations. The paper distinguishes between three basic types: collaborative, competitive, and contentious interaction, all of which are dynamic and can evolve over time. Its findings indicate that contentious interactions are particularly prevalent among asymmetrically capable NSAGs. Using several case studies such as the Syrian Democratic Forces (SDF) or the relations between Hezbollah and the Lebanese Resistance Brigades, the paper argues that rather than collaborative interactions, many ostensible alliances between powerful non-state armed groups and smaller militant organizations should instead be considered specific types of proxy relations, namely non-state sponsorship. In doing so, the paper not only offers a more comprehensive account of how non-state armed groups interact with one another but also expands the scope of research into proxy relationships, which has typically been limited to state-centric approaches.