The Taliban have already taken over control of three gates at Kabul’s airport from US forces and will be in charge of the rest soon, an official from the group said.

“The whole airport is slowly coming under the control of the Taliban,” Enhamullah Samangani, a member of the group’s Cultural Commission, said by telephone. The group is “looking forward to operating the airport after they all leave by Tuesday,” he said.

The US Embassy in Afghanistan told citizens to leave the vicinity of the airport following a “specific, credible threat” of another terrorist attack. US President Joe Biden warned on Saturday that a further attack there is “highly likely” based on an assessment by his military commanders. A suicide bomber on Friday killed at least 88 people, including 13 US service members in the area.

The Western security official, who asked not to be identified, told Reuters a date and time for the end of the operation was yet to be decided.

President Joe Biden has said he will stick by his deadline to withdraw all US troops from Afghanistan by Tuesday, 20 years after they invaded Kabul and ousted the Taliban government for shielding the perpetrators of the Sept. 11, 2001 attacks.

“We want to ensure that every foreign civilian and those who are at risk are evacuated today. Forces will start flying out once this process is over,” said the official, who is stationed at the airport.

The Western-backed government and Afghan army melted away as the Taliban entered the capital on Aug. 15, leaving an administrative vacuum that has bolstered fears of a financial collapse and widespread hunger.

Under a deal with the United States, the Taliban has said it will allow foreigners and Afghans who wish to leave to fly out.

The United States and its allies have taken about 113,500 people out of Afghanistan in the past two weeks, but tens of thousands who want to go will be left behind.

A US official told Reuters on Saturday there were fewer than 4,000 troops left at the airport, down from 5,800 at the peak of the evacuation mission.