US special envoy for Syria Joel Rayburn is leaving his position, US sources confirmed to The National.
Mr Rayburn is one of the main architects of the Syria policy in the Trump administration, having served as senior director for Iran, Iraq, Syria and Lebanon at the National Security Council from January 2017 to July 2018.
From there he was as special envoy at the State Department for Syria.
In November, Mr Rayburn became the acting envoy for the anti-ISIS coalition after the departure of James Jeffrey.
US sources told The National that Mr Rayburn will leave his position shortly, as president-elect Joe Biden is starting to assemble a new, "more cohesive" team on Syria.
Some have said Mr Rayburn would have chosen to stay in the new administration but it was not possible under the Biden team, because of policy and personnel differences.
Mr Rayburn confirmed his departure to The National, saying that it is more due to a routine change during the transition to a new administration than anything else.
“This is a normal rotation of personnel that happens during a transition from one administration to another,” Mr Rayburn said.
The State Department was not immediately available for comment.
He last week told The National that the Trump administration's Syria policy had bipartisan support.
But with Mr Rayburn’s departure and a different team, it is unclear whether Mr Biden will continue with Mr Trump's policy.
During his campaign, the president-elect heavily criticised Mr Trump’s decision to partially withdraw from Syria in 2019.
Mr Biden told the Des Moines Register that the decision gave ISIS "a new lease on life by forcing the Kurds to defend themselves against Turkey instead of fighting ISIS remnants".
His team is expected to increase support to the Syrian Democratic Forces.
On Friday, Mr Biden appointed former diplomat and Pentagon official Brett McGurk as his White House co-ordinator for the Middle East.