A top envoy has quit over Donald Trump's controversial decision to withdraw US troops battling so-called Islamic State in Syria.
Brett McGurk, the US envoy to the global coalition fighting IS, resigned his role on Saturday having previously said it would be "reckless" to consider the militant group defeated.
Mr McGurk's departure comes just days after Jim Mattis stepped down as defence secretary, citing differences in opinion.
President Trump announced on Wednesday the decision to withdraw 2,000 US troops from the fight in Syria, describing their work as complete.
In his resignation letter, Mr McGurk said that though the militants were on the run they were not yet defeated.
He spoke of fears that a premature pullout of American forces could lead to an IS resurgence.
Mr McGurk, whose resignation will be effective from December 31, had been planning to leave his job in mid-February.
But he brought his departure forward over President Trump's decision to withdraw the troops and Mattis's resignation.
Mattis, perhaps the most respected foreign policy official in the administration, announced on Thursday that he will leave by the end of February.
He told President Trump in a letter that he was departing because "you have a right to have a Secretary of Defense whose views are better aligned with yours."
Pulling troops from Syria has long been a goal of the US president.
Mr McGurk said at a State Department briefing on December 11 that "it would be reckless if we were just to say, 'Well, the physical caliphate is defeated, so we can just leave now.' I think anyone who's looked at a conflict like this would agree with that."