U.S. Ambassador James Jeffrey is stepping down this month from his posts as U.S. special representative for Syria engagement and special envoy for the global coalition to defeat Daesh, Secretary of State Mike Pompeo announced Monday.

Pompeo said Joel Rayburn, the current deputy assistant secretary for Levant affairs and special envoy for Syria, will replace Jeffrey as the special representative for Syria. Ambassador Nathan Sales, the State Department's coordinator for counterterrorism, has been designated as anti-Daesh coalition special envoy.

Jeffrey, a former U.S. ambassador to Turkey, was appointed as the State Department's Syria point person in August 2018, later assuming the role of special envoy for the Daesh coalition in January 2019.

"He achieved remarkable results in each capacity, advancing our efforts toward a political resolution to the Syrian crisis and creating the conditions for an enduring defeat of ISIS," Pompeo said in a written statement, referring to Daesh terrorist group with an alternate acronym.

Pompeo highlighted Jeffrey's efforts to "build and maintain an international coalition that greatly increased the economic and political pressure on the Assad regime" and achieve the "territorial defeat" of the Daesh terrorist group.

The secretary of state expressed his "deepest appreciation" for Jeffrey's 45 years of service in the army and foreign service.