“I was not aware of the specific announcement,” General Joseph Votel, commander of U.S. Central Command, told the House Armed Services Committee Tuesday, according to CNN. In general, he said officials were “aware that he had expressed a desire and intent in the past to depart Iraq, depart Syria.”

Votel added that he was “not consulted” on the matter, and warned that the terrorist group known as the Islamic State still remains a threat, echoing recent reports from other top intelligence officials. According to Votel, ISIS still controls about 20 square miles in Syria, with up to 1,500 fighters.

“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,” said Votel, TIME reports.

Still, Votel said the military would execute Trump’s orders for withdrawal “in a very deliberate manner.” While he said he’s not expected to have the 2,000 American troops out of Syria by a specific date, TIME reports military officials believe the withdrawal will be completed by spring.

Trump first announced the withdrawal of troops on December 19, tweeting that the U.S. “defeated ISIS in Syria.” The sudden claim rattled top security advisers, and led former defense secretary Jim Mattis to resign from his post.

National Security Adviser John Bolton has since stated that the U.S. will only withdraw once ISIS is defeated and the safety of allied Kurdish fighters is secured, although Trump said plans remain unchanged.

Votel warned that ISIS could regroup with the removal of U.S. troops, meaning the military will have to “keep pressure on this network” even after withdrawal.

“I won’t speculate publicly here about things we might do but there are certainly different ways we can do this, working with partners, working with our own capabilities to continue to keep pressure on this network which I think is absolutely vital,” Votel explained.