President Donald Trump did not consult his top military commander in the Middle East before making the abrupt announcement to withdraw all 2,000 U.S. troops from Syria.

General Joseph Votel, the four-star Army commander who heads U.S. Central Command, made the disclosure Tuesday during an appearance before the Senate Armed Services Committee about the withdrawal orders.

“I was not consulted,” he said, adding that he was broadly aware of Trump’s “desire and an intent in the past to depart Syria.”

When Trump announced his decision to pullout on Dec. 19, it sent shock waves through Washington and the rest of the world. “Our boys, our young women, our men, they’re all coming back and they’re coming back now. We won,” the president said in a video posted on Twitter.

The ensuing chaos led to the high-profile resignations of Defense Secretary James Mattis and Brett McGurk, the State Department’s special envoy to the coalition fighting ISIS. “The recent decision by the president came as a shock and was a complete reversal of policy that was articulated to us,” McGurk wrote in an email to colleagues obtained by the New York Times. “It left our coalition partners confused and our fighting partners bewildered.”

Votel confirmed he was among those left in the dark, telling the Senate panel: “I was not aware of the specific announcement.”

The GOP-led Senate approved legislation Tuesday afternoon that criticized Trump’s planned troop pullout from Syria and Afghanistan. The 77-23 vote on the Strengthening America’s Security in the Middle East Act was non-binding, but delivered a rare Republican rebuke to the president just hours before his State of the Union speech.

The U.S. already started the withdrawal process earlier this month when the military hauled vehicles and equipment from northeast Syria into neighboring Iraq. No timeline has been publicly discussed as to when the withdrawal of all American forces will be completed, but military officials expect it to be out by spring.

“We are adjusting our military posture in Syria, planning and executing a deliberate, safe and professional withdrawal of personnel and equipment while preserving sufficient power in the region,” Votel said.

The Pentagon is currently wrestling with questions on how the pullout can be handled, including what the U.S. can do to help protect its Kurdish partners and maintain the 79-member international coalition aimed at eradicating ISIS.

The Sunni Muslim extremist group has lost roughly 99% of its territory in Iraq and Syria. But ISIS has expanded and established cells around the world, and routinely mounts attacks in Syria, such as the Jan. 16 suicide bombing that killed four Americans at a restaurant in Manbij.

A new Department of Defense Inspector General report made public Monday said that “absent sustained pressure,” ISIS would re-emerge in Syria within six to 12 months. The report also stated that ISIS leadership retains “excellent command and control capability” in Syria and continues to attract an estimated 50 foreign fighters to Syria and Iraq each month.

Votel said ISIS now controls a scrap of territory that takes up less than 20 square miles in eastern Syria. Previously, the group was in control of vast swathes of Iraq and Syria, an area roughly the size of Britain. “It is important to understand that even though this territory has been reclaimed, the fight against ISIS and violent extremists is not over and our mission has not changed,” Votel said.

In August, the Pentagon published another inspector general report which said the U.S. military estimates that ISIS has as many as 30,000 fighters in Iraq and Syria. A United Nations report published that same month made a similar assessment.

Votel said he had “low to medium confidence” in those estimates.

The militants’ ability to quickly reconstitute raises questions about pulling the troops out and trying to keep up the pressure from afar. In an interview with CBS on Sunday, Trump said U.S. troops would first be deployed to Iraq, then back stateside — all the while watching ISIS in Syria.

“We’ll come back if we have to,” Trump said. “We have very fast airplanes, we have very good cargo planes. We can come back very quickly, and I’m not leaving. We have a base in Iraq and the base is a fantastic edifice. I mean I was there recently, and I couldn’t believe the money that was spent on these massive runways. And these — I’ve rarely seen anything like it. And it’s there. And we’ll be there.”

The counter-ISIS battle in Syria is different in many ways than past U.S. wars. There are few U.S. troops on the ground actually fighting or providing targeting information. American Special Operations forces inside Syria coordinate with local opposition fighters called the Syrian Democratic Forces, an alliance of mostly Kurdish and Arab fighters. U.S. forces train and advise the group.

U.S. military commanders rely heavily on Syrian forces to gather intelligence from information and material gathered from the battlefield, but also a wide-range of informers with firsthand knowledge about ISIS operations. If U.S. troops are not on the ground in Syria, counter-terrorism analysts fear Americans access to those intelligence streams may dry up.

“It’s always best to be with your partners,” Votel said.

Write to W.J. Hennigan at william.hennigan@time.com.