The U.S. has started withdrawing forces from Syria, a spokesman for allied coalition forces said Friday, a month after President TrumpDonald John TrumpGovernment workers protest outside White House on shutdown day 20 Fed chief Powell: Prolonged shutdown will harm US economy Senators say questions remain on Trump strategy in Syria after briefing MORE's announcement of his plan to do so caused ripples in Washington and was credited with causing high-ranking departures in the Trump administration.
The military “has begun the process of our deliberate withdrawal from Syria. Out of concern for operational security, we will not discuss specific timelines, locations or troop movements,” Ryan said in a statement.
It wasn't initially clear how many troops would be withdrawn in the first wave of departures from Syria, or how many would remain working with anti-ISIS coalition forces after Trump's plan was enacted.
Trump's decision to withdraw from Syria, announced last month, was considered to be the main reason for the resignations of Defense Secretary James Mattis and coalition forces special envoy Brett McGurk.
Other top Pentagon aides, including Mattis's chief of staff and Pentagon spokeswoman Dana White, have also resigned in the past month.
In a statement announcing his departure in December, Mattis appeared to rebuke the president's treatment of U.S. allies in the Middle East and elsewhere around the world, while stating that Trump deserved a defense secretary more closely aligned with his political beliefs.
“Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position,” Mattis wrote in his resignation letter.