The airstrike came a day after President Biden vowed to retaliate for a terrorist attack that killed 13 US service members and at least 170 others

“U.S. military forces conducted an over-the-horizon counterterrorism operation today against an ISIS-K planner. The unmanned airstrike occurred in the Nangarhar Province of Afghanistan,” spokesman Capt. Bill Urban said Friday. “Initial indications are that we killed the target. We know of no civilian casualties.”

The identity of the person targeted in the US airstrike has not yet been confirmed.

The US Embassy in Kabul on Friday again warned US citizens at a number of gates at Hamid Karzai International Airport to “leave immediately,” citing security threats.

The alert advised US citizens “to avoid traveling to the airport and to avoid airport gates.”

Following Thursday’s attack, Biden’s national security team told him Friday that “another terror attack in Kabul is likely, but that they are taking maximum force protection measures at the Kabul Airport,” according to White House press secretary Jen Psaki.

“The next few days of this mission will be the most dangerous period to date,” Psaki said in a statement Friday.

Thousands more flown out

Flights could be seen taking off from the airport Saturday morning but it was unclear how many people were still seeking to get to the airport and out of the country.

Far fewer people were at the airport Friday, and a source directly familiar with the Kabul airport operations told CNN the remaining focus was to get people with special, last-minute access requests to the airport. But the source cautioned that officials were “unsure how many they can get in with so much Taliban coordination required.”

The Pentagon said the US was “still planning on ending this mission at the end of the month,” representing a final exit from a 20-year war in Afghanistan.

The US has evacuated and facilitated the evacuation of approximately 109,200 people since August 14, according to the White House.

About 4,200 people were evacuated from Kabul from 3 a.m. to 3 p.m. ET on Friday, according to the White House. The evacuations were carried out by 12 US military flights that carried approximately 2,100 evacuees and 29 coalition flights that also evacuated about 2,100 people.

Approximately 7,500 people had been evacuated from Kabul in the same 12-hour period the day before.

State Department spokesperson Ned Price said earlier Friday that “there are approximately 500 American citizens we are currently working with who want to leave and with whom we are communicating directly to facilitate their evacuations.”

US allies conclude evacuations

The head of the United Kingdom’s armed forces, Gen. Nick Carter, said the UK’s effort to evacuate Afghan civilians from the country would end Saturday, to be followed by the withdrawal of the remaining UK troops.

“It’s gone as well as it could do in the circumstances… but we haven’t been able to bring everybody out and that has been heartbreaking and there have been some very challenging judgements that have had to be made on the ground,” he told BBC Radio 4.

The number left behind who were eligible to be brought to the UK was in the “high hundreds” he said.

The defense spokesman for the opposition Labour Party, John Healey, told Sky News that despite the UK getting more than 14,000 people out of the country, “there are probably 1,000 Afghans who have worked with us over two decades in Afghanistan, helped our troops, our aid workers, our diplomats, that we promised to protect, but we’re leaving behind.”

Healey urged UK Prime Minister Boris Johnson to intervene to offer hope of rescue to those Afghans left behind.

France announced the end of its evacuation effort Friday but vowed to “stand by the Afghan people” after August 31, in a statement released by Foreign Minister Jean-Yves Le Drian and Armed Forces Minister Florence Parly.

The country had evacuated nearly 3,000 people since August 15, the statement said. An extra 1,500 Afghans who had worked for France were evacuated before August 15 in anticipation of the current crisis, it added.

Italy’s Defense Ministry also said Friday that it had concluded its military evacuations of Afghan nationals out of Kabul.

The last flight took off Friday evening carrying 58 Afghan citizens, with the remainder of those on board Italian service members involved in the evacuation process, the ministry said. Since June, 5,011 people have been evacuated in total, of whom 4,980 are Afghan citizens, including 1,301 women and 1,453 children, it said.

Australia, New Zealand, Sweden, Belgium, the Netherlands, Poland, Turkey and Spain have all said their evacuation missions ended or were scheduled to end on Friday.

Meanwhile, the World Health Organization said Friday that it was trying to establish an air bridge into the city of Mazar-i-Sharif in Northern Afghanistan in the coming days, with the help of Pakistan authorities.