The White House abruptly announced on Wednesday that the United States will begin withdrawing the 2,000 troops in Syria fighting ISIS, contradicting senior administration officials in charge of regional policy and leaving the details of the drawdown murky.

It was a swift and apparently unilateral reversal of U.S. policy that appeared to have been decided by President Trump without the kind of robust interagency deliberation that would traditionally accompany such a significant strategic move. The announcement threw Capitol Hill into chaos as blindsided lawmakers demanded briefings from Trump officials who appeared to have been equally shocked. Just an hour before the announcement, the Pentagon was telling reporters that the U.S. was continuing to work with partners in the region. After a series of calls with senior officials, Senate Foreign Relations Chairman Bob Corker, R-Tenn., told reporters, “I don’t get the sense that there was any interagency process.”

“My sense is it’s been a shock throughout the administration that this type of decision was made,” he said, suggesting that the president “just woke up” and ordered the withdrawal. He added that to his knowledge, key allies in the regional fight against ISIS were also not informed.

On Wednesday morning, President Trump tweeted that ISIS in Syria has been “defeated,” calling the counter-ISIS mission “my only reason for being there”; shortly afterwards, the White House issued a more narrow statement that the administration has started sending troops home now that “the United States has defeated the territorial caliphate.”

The announcement left unanswered a host of questions, in particular about the timing of the drawdown and whether U.S. forces will continue to offer air support to partners battling the remnants of the Islamic State. “These victories over ISIS in Syria do not signal the end of the global coalition or its campaign,” Press Secretary Sarah Huckabee Sanders said, calling the drawdown a transition to “the next phase of this campaign.”

Senior officials and regional experts say say Trump’s assertion that ISIS in Syria has been defeated is untrue, although significant territorial gains have been made. Officials say thousands of extremist fighters are still operating in Syria and the pace of military operations remains brisk; last week alone, the U.S.-led coalition carried out over 200 airstrikes. Trump’s tweet swiftly drew comparisons to former President George W. Bush’s now-infamous “Mission Accomplished” speech on the deck of the USS Abraham Lincoln in 2003, announcing a victory in Iraq that was far from achieved.

In September, the senior diplomat in charge of Syria, Ambassador Jim Jeffrey, announced a “new policy” that indefinitely extended U.S. military and diplomatic engagement there, in part to include an effort to thwart the Iranian military and proxy presence there. For months, top Pentagon and State Department officials have said that although the fight to reclaim territory from ISIS is almost over, U.S. forces would remain in Syria to stabilize the country and prevent a resurgence of the extremist group, as well as serve as an indirect check on Iran.

“I'm not at all complacent about the work that remains to be done,” Chairman of the Joint Chiefs of Staff Joseph Dunford said at an event last month. “I would say we're well along in clearing ISIS from the ground that they've held in Syria and we still have a lot of work to do in terms of the stabilization phase.”

Top Defense Department spokesperson Dana White said that the Pentagon would not provide details on the number and timing of returning troops “for force protection and operational security reasons.”

Trump has long said publicly that he wanted to “get out” of Syria. A senior administration official sought to explain the policy reversal in a hastily-scheduled press call that afternoon by arguing that Trump himself has been consistent. But Jeffrey told reporters in September that he was “confident the president is onboard” with the new policy. And key Republicans on Capitol Hill were unconvinced—and in some cases, outright alarmed.

“Eight days ago the Administration called a hypothetical pullout ‘reckless.’ Today, we're leaving. The President's generals have no idea where this weak decision came from,” said Sen. Ben Sasse, R-Neb., a member of the Senate Armed Services Committee.

Despite the murky circumstances surrounding the withdrawal, Corker said that based on conversations with people close to the decision, he believed the president has “made up his mind.”

“I don’t know that there’s any way to reverse it,” he said. “It’s obviously a political decision.”

Trump did receive praise from one unlikely quarter: Democratic Rep. Ted Lieu, Calif., a former Air Force prosecutor, said he “applauded” the decision.

“Neither the Obama Administration nor the Trump Administration had a strategy. Neither Administration could articulate why we were in Syria, what the end state would be, and how we would achieve it,” Lieu said in a tweet.

The snap decision comes just days after a phone call between Trump and Turkish President Recep Tayyip Erdogan. The senior administration official insisted that the president did not discuss the Syria withdrawal with Erdogan. Erdogan has said that he told Trump that he would soon launch an offensive against Kurdish troops in northern Syria, backed by the U.S. in the fight against ISIS but which Turkey considers part of a terrorist group.

According to The New York Times, senior Defense Department officials were working as late as Wednesday morning to convince Trump not to pull out—in part, they argued, because the withdrawal would betray America’s Kurdish and Arab allies in the Syrian Democratic Forces, now under threat of a military offensive by Turkey. It would also broadly damage efforts to convince local fighters to work with American forces, critics say, by showing that the U.S. is not a reliable partner.

Pressed to explain why Trump is overriding his senior advisors, the senior administration official said that Trump was acting within his authority as commander in chief.

“The issue here is that the president has made a decision,” the official said. “He gets to do that. That’s his prerogative.”

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