BEIRUT — The U.S. military said Friday it has begun withdrawing troops from Syria, initiating a drawdown that has blindsided allies and sparked a scramble for control of the areas that American troops will leave.

U.S. forces have “begun the process of our deliberate withdrawal from Syria,” read a statement from the U.S.-led coalition. “Out of concern for operational security, we will not discuss specific timelines, locations or troop movements.”

President Trump’s Dec. 19 announcement that he was moving to disentangle some 2,000 U.S. troops from Syria’s complex battlefield sparked fears that the move might undo efforts to defeat the Islamic State’s final remnants in Syria.

It also marked the culmination of years of criticism by Trump over Washington’s role in foreign wars. In public statements, he had repeatedly suggested that he wanted to bring American troops back home.

But following a backlash from Republicans and Democrats in Congress and the resignation of Defense Secretary Jim Mattis, Trump said the troops would be withdrawn “slowly.”

Extending the timeline further, national security adviser John Bolton said Sunday that the pullout was conditional on the defeat of the last remnants of the Islamic State and guarantees from Turkey that it would not attack Kurdish forces aligned with the United States.

But Turkish President Recep Tayyip Erdogan made clear this week that he would not agree to those terms and lashed out at Trump’s aide. “It is not possible for us to swallow the message Bolton gave,” Erdogan said.

Secretary of State Mike Pompeo confirmed that U.S. troops would withdraw from the country on Wednesday but did not give a timeline, and said U.S. officials were still in discussions with Turkey on ensuring the safety of Kurdish forces.

A spokesman for the National Security Council, Garrett Marquis, said Bolton and other senior U.S. officials conveyed to Turkish officials a set of principles for the U.S. withdrawal, which includes opposition to any mistreatment of forces who fought with the United States in Syria.

Fearing that possibility, Kurdish officials have turned to Russia, a key ally of Syrian President Bashar al-Assad. They are hoping that Moscow can broker a deal that would see the Syrian government filling any power vacuum left by the American withdrawal, and in the process, head off any Turkish incursion.

Pompeo: America ‘will not retreat’ until fight against terror is over

During a Jan. 10 speech in Cairo, Secretary of State Mike Pompeo addressed President Trump’s recent decision to withdraw U.S. troops from Syria. (Reuters)

The Syrian Observatory for Human Rights, a Britain-based monitoring group, said sources in Syria’s northeastern province of Hasakah reported the departure of about 150 vehicles and roughly the same number of personnel from a military base in the town of Rmelan late Thursday.

The group also published a dash-cam video appearing to show some of the trucks travelling along the road to Kobane, a town on the Turkish border that became the site of one of the U.S.-led coalition’s most high profile early battles against the Islamic State.

That report could not be independently confirmed, and it was unclear whether the movement indicated a drawdown or was just a planned rotation.

Pompeo, who is in the middle of a nine-country trip to the Middle East, has tried to convince U.S. allies that the withdrawal will not alter the Trump administration’s mission to fully defeat the Islamic State and drive out Iran from Syria, a common talking point.

“This isn’t a change of mission,” Pompeo said in a speech in Cairo on Thursday. “In Syria, the United States will use diplomacy and work with our partners to expel every last Iranian boot.”

But experts doubt Washington’s ability to oust Iran without a massive influx of troops, and Trump himself has spurned the value of opening a new front in Syria, saying the country offered nothing but “sand and death.”

Foreign allies, including the Kurdish-led force that has spearheaded Washington’s fight against the Islamic State, say they received no warning about the withdrawal announcement, and administration officials initially offered differing timetables for its completion.

Representatives of the Syrian Democratic Forces, a military coalition dominated by Kurdish fighters, declined to comment Friday, suggesting instead that the U.S. military should explain its plans.

Hudson reported from Abu Dhabi, United Arab Emirates. Missy Ryan contributed to this report from Washington, D.C.