He is one of the few names to have served under George W Bush, Barack Obama and Donald Trump. But now, Brett McGurk, the special US envoy in the war against ISIS, is calling it quits, making him the second senior US official to leave the Trump administration over an abrupt decision to withdraw US troops from Syria.
Mr McGurk also joins the disenfranchised ranks of fired and retired officials such as former secretary of state Rex Tillerson and White House chief of staff John Kelly, who departed only two weeks ago.
Mr McGurk, whose resignation is effective December 31, submitted his notice to US Secretary of State Mike Pompeo on Friday, CBS reported. Taking over for now for Mr McGurk will be his deputy, retired Lt Gen Terry Wolff, who served three tours of duty in Iraq.
In his resignation letter, Mr McGurk said that the militants were on the run but not yet defeated and that the premature pull-out of American forces from Syria would recreate the conditions that gave rise to ISIS, according to the Associated Press.
While Mr McGurk was planning to leave in February 2019, his exit this week came after Mr Trump announced a rushed withdrawal plan of an estimated 2,000 troops from Syria.
His resignation comes at a difficult time for the US, with the government partially shut down in a fierce dispute over Mr Trump's demands that Congress assign $5 billion for a wall along the border with Mexico.
It also comes only days after US Secretary of Defence James Mattis said he would be leaving his position in February after differences with US President Donald Trump that include his recent decision to withdraw troops from Syria.
Mr Trump announced his Syria exit following a call with Turkish President Recep Tayyip Erdogan around ten days ago. Turkish officials have heavily criticised Mr McGurk in the past.
In May 2017, Turkish Foreign Minister Mevlut Cavusoglu openly called openly for his replacement. “Brett McGurk is definitely giving support to the PKK [The Kurdistan Workers' Party] and YPG [The People's Protection Units],” Mr Cavusoglu said, referring to two Kurdish militias that Ankara has designated as terrorist groups.
"It would be useful if this person was replaced," he told NTV television.
Mr McGurk has played an instrumental role in managing stabilisation and reconstruction efforts in areas liberated from ISIS in Syria and Iraq, earning him esteem from US allies who contributed millions of dollars for post-conflict recovery efforts.
With him gone, and a US withdrawal approaching, it is unclear what will happen to US-backed reconstruction efforts in Iraq and Syria.
Mr McGurk opposed a rushed withdrawal from Syria and was at odds with Mr Trump's view that ISIS is defeated. Only last week he said "it would be reckless if we were just to say, well, the physical caliphate is defeated, so we can just leave now".
Mr Trump responded to news of Mr McGurk's resignation on Twitter, saying the latter's departure may be a case of grandstanding.
On Saturday, he reiterated his plans to withdraw, despite growing criticism from within his administration, especially among senior defence officials
“Other local countries, including Turkey, should be able to easily take care of whatever remains [of ISIS]. We’re coming home,” he said on Twitter.
More resignations could be expected at the Pentagon, Fox News reported on Friday.
Jim Jeffrey, a veteran diplomat who was appointed special representative for Syria engagement in August, is expected to stay in his position, officials said.