Local alliances and rivalries shape near-repeat terror activity of al-Qaeda, ISIS, and insurgents
Significance We examine near-repeat activity patterns of al-Qaeda, ISIS, and local insurgents, whereby a first terrorist attack temporarily increases the likelihood of a second one by the same group. We observe heightened near-repeat activity for all organizations in six geographic clusters and quantify the effect to persist within 20 km and 4 to 10 weeks after the first event. Near-reaction patterns, where two distinct groups react to each other’s activities, depend on the adversarial, neutral, or collaborative relationship between parties at the local level. We find no evidence of outbidding, whereas terrorist and state activities mutually reinforce one another. Our results may be useful for counterterrorism decision making and strategic resource allocation; near-repeat patterns may offer insight into local power structures. We study the spatiotemporal correlation of terrorist attacks by al-Qaeda, the Islamic State of Iraq and Syria (ISIS), and local insurgents, in six geographical areas identified via k-means clustering applied to the Global Terrorism Database. All surveyed organizations exhibit near-repeat activity whereby a prior attack increases the likelihood of a subsequent one by the same group within 20 km and on average 4 (al-Qaeda) to 10 (ISIS) weeks. Near-response activity, whereby an attack by a given organization elicits further attacks from a different one, is found to depend on the adversarial, neutral, or collaborative relationship between the two. When in conflict, local insurgents respond quickly to attacks by global terror groups while global terror groups delay their responses to local insurgents, leading to an asymmetric dynamic. When neutral or allied, attacks by one group enhance the response likelihood of the other, regardless of hierarchy. These trends arise consistently in all clusters for which data are available. Government intervention and spillover effects are also discussed; we find no evidence of outbidding. Understanding the regional dynamics of terrorism may be greatly beneficial in policy making and intervention design.