Brett McGurk, the US envoy to the global coalition fighting Islamic State, has resigned in protest over the decision to withdraw American troops from Syria.
McGurk joins Defence Secretary Jim Mattis in an exodus of experienced national security officials.
Only 11 days ago, McGurk said it would be “reckless” to consider IS defeated and therefore would be unwise to bring American forces home.
He has decided to speed up his plan to leave in mid-February.
He said in his resignation letter that the militants were on the run, but not yet defeated, and that the premature pullout of American forces from Syria would create the conditions that gave rise to IS.
McGurk also cited gains in accelerating the campaign against IS, but that the work was not yet done.
His resignation letter, submitted on Friday to Secretary of State Mike Pompeo, was described to The Associated Press on Saturday by an official familiar with its contents, who spoke on condition of anonymity.
Trump played down the development, tweeting on Saturday night that “I do not know” the envoy and it’s a “nothing event.”
He noted McGurk planned to leave soon anyway and added: “Grandstander?”
Shortly after news of McGurk’s resignation broke, Trump again defended his decision to pull all of the roughly 2000 US forces from Syria in the coming weeks.
“We were originally going to be there for three months, and that was seven years ago – we never left,” Trump tweeted.
“When I became President, ISIS was going wild. Now ISIS is largely defeated and other local countries, including Turkey, should be able to easily take care of whatever remains. We’re coming home!”
Although the civil war in Syria has gone on since 2011, the US did not begin launching airstrikes against the Islamic State until September 2014, and American troops did not go into Syria until 2015.
McGurk, whose resignation is effective December 31, was planning to leave the job in mid-February after a US-hosted meeting of foreign ministers from the coalition countries, but he felt he could continue no longer after Trump’s decision to withdraw from Syria and Mattis’ resignation, according to the official.
Trump declaration of a victory over IS has been roundly contradicted by his own experts’ assessments, and his decision to pull troops out was widely denounced by members of Congress, who called his action rash and dangerous.
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 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.”
The withdrawal decision will fulfil Trump’s goal of bringing troops home from Syria, but military leaders have pushed back for months, arguing that the IS group remains a threat and could regroup in Syria’s long-running civil war.
US policy has been to keep troops in place until the extremists are eradicated.