Pré-publication, Document de travail: The effectiveness of security operations often depends on cooperation between different national armies. Such cooperation can be particularly important when international borders are porous. In this project, we investigate how the creation of an international armed force that could operate across international borders (the G5-Sahel Joint Force) affected conflict dynamics in the Sahel region. Relying on a regression discontinuity design, we find that the G5 mission lowered the intensity of conflict locally in its zone of operation. Further analysis of geographical conflict propagation patterns indicates that the G5-Sahel force facilitated security operations in border areas.