Do states circumvent embargoes by supplying weapons across borders to sanctioned countries? We report evidence that arms imports systematically increase in the neighborhood of conflict states under an embargo. Using several alternative research-design specifications, we contend that this pattern is consistent with arms exporters shifting the arms trade to neighbors of conflict states under sanctions, where it is easier to move arms clandestinely across the border. Despite the lack of direct evidence of clandestine cross-border…