The United States military has struck back at ISIS, bombing a member of the militant group in Afghanistan less than 48 hours after a devastating suicide bombing claimed by ISIS killed as many as 169 Afghans and 13 American service members at the Kabul airport.

US Central Command said the US conducted a drone strike against an Islamic State member in Nangahar believed to be involved in planning attacks against the US in Kabul. The strike killed one individual, and spokesman Navy Captain William Urban said they knew of no civilian casualties.

It wasn't clear if that individual was involved specifically in the Thursday suicide blast outside the gates of the Kabul airport, where crowds of Afghans were desperately trying to get in as part of the ongoing evacuation from the country after the Taliban's rapid takeover.

The airstrike fulfilled a vow President Joe Biden made to the nation Thursday when he said the perpetrators of the attack would not be able to hide. "We will hunt you down and make you pay," he said.

Pentagon leaders told reporters Friday that they were prepared for whatever retaliatory action the president ordered. "We have options there right now," said Major General Hank Taylor of the Pentagon's Joint Staff.

Biden ordered US flags to half-staff across the country in honour of the 13 Americans killed in the Kabul attack.

They were the first US service members killed in Afghanistan since February 2020, the month the Trump administration struck an agreement with the Taliban that called for the militant group to halt attacks on Americans in exchange for a US agreement to remove all American troops and contractors by May 2021. Biden announced in April that he would have all forces out by September.

White House Press Secretary Jen Psaki said the next few days of the mission to evacuate Americans and others, including vulnerable Afghans fleeing Taliban rule, "will be the most dangerous period to date". Biden has set Tuesday as the deadline for completing the airlift.

The White House said that as of Friday morning, about 12,500 people were airlifted from Kabul in the last 24 hours on US and coalition aircraft; in the 12 hours that followed, another 4,200 people were evacuated.

Psaki said about 300 Americans had departed and the State Department was working with about 500 more who want to leave. The administration has said it intends to push on and complete the airlift despite the terror threats.