Iran’s Revolutionary Guard Corps shot down a U.S. surveillance drone over the Strait of Hormuz on Thursday, claiming it had entered Iranian airspace — which the U.S. military disputes. The incident was the most alarming one in a week of increasing tensions in the Persian Gulf.

On Monday, a spokesman for Iran’s Atomic Energy Organization threatened that within 10 days, Iran might breach the nuclear-enrichment restrictions imposed by the Joint Comprehensive Plan of Action (JCPOA), the 2015 nuclear deal between Iran and major world powers from which the Trump administration has withdrawn. In response, the United States announced the deployment of an additional 1,000 American troops to the Middle East. On Tuesday, Secretary of State Mike Pompeo said that President Trump “does not want war” but warned that U.S. troops would respond with force to Iranian aggression. At a campaign rally that night, Trump bragged about getting out of the “disastrous” Iran deal and imposing “the toughest-ever sanctions” on Iran before saying he’s “charting a path to stability and peace in the Middle East.”