Patterns in conflict dynamics in Yemen and Syria

Abstract Conflict fatalities tend to follow heavy-tailed statistical distributions. A 2005 fusion–fission theory predicts that, when armed groups operate through dynamically forming and fragmenting clusters, the number of fatalities per event should be approximated by a power-law distribution with exponent α near 2.5, with deviations reflecting the relative robustness of larger versus smaller fighter clusters. We use Armed Conflict Location and Event Data (ACLED) event-level fatality data to estimate α in recent Yemen and Syria conflict periods during 2023–2025. These conflict event datasets are small, incomplete and imperfect and only produce very crude approximations to a power law; nonetheless, the best-fit α values occupy the range 2.5<α<3.5 across most periods, which is broadly consistent with predominantly fragmented or weakly consolidated armed-group organization. Temporary reductions in α are broadly consistent with episodes in which larger coordinated clusters become more consequential. More rigorous testing will require improved datasets to become available in the future.