Type: Article
Publication Date: 2019-09-30
Citations: 15
DOI: https://doi.org/10.1073/pnas.1904418116
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.