Brett McGurk was outraged. Without consulting his team, let alone U.S. allies, President Donald Trump announced on Oct. 6, 2019, that the United States would not only abandon Syrian Kurdish fighters with whom it had allied in order to defeat the Islamic State but also greenlight a Turkish invasion of northern Syria.

Defense Secretary James Mattis resigned, and McGurk quickly followed. Within days, Turkish forces had moved south into Syria’s most stable and democratic region, where they prioritized repression of Kurds, Christians, and Yazidis over defeat of the Islamic State.