On June 20, U.S. military officials confirmed media reports that Iranian military forces successfully shot down a U.S. drone in the vicinity of the Persian Gulf. Though several relevant details regarding the incident remain unclear or in dispute—including whether the drone had ventured into Iranian airspace before it was shot down—this is the most significant encounter between the two sides in the current period of high tensions and may prove to be a major step toward a broader armed conflict. And for the United States, it raises the more immediate legal question of whether and how President Trump may choose to respond militarily.

Scott R. Anderson & Ashley S. Deeks, Iran Shoots Down a U.S. Drone: Domestic and International Legal Implications, Lawfare (June 20, 2019).