With Friends Like These…Why Terrorist Organizations Ally

Why do terrorist organizations ally with one another? To answer this question, we use data from the Big Allied and Dangerous (BAAD) Version 1.0 dataset to estimate an exponential random graph (ERGM) model of terrorist organizational ties. Our analysis focuses on 14 hypotheses that are drawn broadly from the organizational, network, social movements, and general political science literatures. Our analysis finds that alliances tend to form between organizations that share motivation (especially if the potential partners are both Islamic or both ethno-nationalist in their motivation), are relatively similar in age, seek to target the same country, are drawn from the same region, and are based in countries with small militaries. Overall, terrorist organizations tend to prefer network structures that are organized into cliques or subgroups, though with some outreach to clusters beyond their primary partners.