Joe Biden warned on Saturday that another terrorist attack in Kabul was highly likely in the next 24 to 36 hours, and said the US drone strike which killed two Islamic State targets in retaliation for the deaths of 13 US service members and as many as 170 civilians on Thursday would not be the last such action.

Earlier, Pentagon spokesmen said 6,800 people had been flown from Afghanistan in the last 24 hours, bringing the total of US citizens and Afghan allies evacuated in one of the biggest airlifts in history to more than 117,000.

The Pentagon also named the US service members killed by a suicide bomber and gunmen at the airport in Kabul on Thursday.

Eleven were US marines, one was a soldier and one a sailor. Many were only babies when the US invaded Afghanistan in late 2001.

Ahead of the 31 August deadline for the US withdrawal from Taliban-held Kabul, Pentagon officials said the military had begun to pull out. As of Saturday, an official told Reuters, there were fewer than 4,000 US troops at the Kabul airport, down from 5,800 at the peak of the evacuation.

In a statement from the White House, where he was also preparing for the landfall of a major hurricane in Louisiana, Biden said he had met with national security advisers.

“We discussed the strike that US forces took [on Friday] night against the terrorist group Isis-K in Afghanistan,” he said.

The Pentagon said the drone attack killed two Islamic State “planners and facilitators”.

Biden said: “I said we would go after the group responsible for the attack on our troops and innocent civilians in Kabul, and we have.

“This strike was not the last. We will continue to hunt down any person involved in that heinous attack and make them pay. Whenever anyone seeks to harm the United States or attack our troops, we will respond.”

The Taliban condemned the strike as a “clear attack on Afghan territory”.

A spokesman, Zabihullah Mujahid, also told reporters the Taliban expected to take full control of Kabul airport once US forces leave. On Saturday, Taliban fighters set up new layers of checkpoints on roads leading to the airport, some manned by uniformed fighters with Humvees and night-vision goggles captured from Afghan security forces.

The spokesman also said the militants were preparing to form a government, and would soon announce a full cabinet. Officials had been appointed to run key institutions, the spokesman said, including the ministries of public health and education and the central bank. The spokesman also said he expected serious economic turbulence to ease soon.

About 5,400 Americans have been evacuated from Afghanistan so far, including 300 in the last day. The state department said it believed about 350 more wanted to get out and about 280 others who had said they were Americans had either not described plans to leave the country or had said they planned to remain.

John Kirby, the Pentagon spokesman, told reporters the drone strike would not be sufficient to stop Islamic State terrorists in their tracks.

“They have lost some capability to plan and to conduct missions,” he said, “but make no mistake, nobody’s writing this off and saying, ‘Well, we got them. We don’t have to worry about Isis-K any more.’ Not the case.”

Biden said the situation in Kabul “continues to be extremely dangerous, and the threat of terrorist attacks on the airport remains high. Our commanders informed me that an attack is highly likely in the next 24 to 36 hours.

“I directed them to take every possible measure to prioritise force protection, and ensured that they have all the authorities, resources and plans to protect our men and women on the ground. They assured me that they did, and that they could take these measures while completing the mission and safely retrograding our personnel.”

The president said the US service members killed on Thursday were “heroes who made the ultimate sacrifice in service of our highest American ideals and while saving the lives of others”.

“Their bravery and selflessness has enabled more than 117,000 people at risk to reach safety thus far,” he said. “May God protect our troops and all those standing watch in these dangerous days.”