James Jeffrey, the career diplomat overseeing the Trump administration’s policies on Syria and the Islamic State (IS), is stepping down, the US State Department announced on Monday.

Jeffrey came out of retirement in 2018 to serve as the State Department’s special representative for Syria. And following the resignation of Brett McGurk, he took on the added job of lead US envoy for the international anti-IS coalition.

The 74-year-old veteran of the State Department leaves behind a complicated legacy on Syria. He and his team were caught off guard when Trump effectively greenlit Turkey’s October 2019 invasion of northeast Syria, which many in Washington saw as an abandonment of the US-allied Kurdish forces who helped defeat IS.

“Jeffrey believed the US could find common ground with Turkey in Syria long after many others had given up hope,” said Nicholas Danforth, senior research fellow at the Hellenic Foundation for European and Foreign Policy. “Both diehard critics and advocates of America’s alliance with the [People's Protection Units] ultimately came to agree that this was a quixotic if not dangerous effort.”