President Joe Biden’s national security adviser said on Sunday that the US is concerned about the possibility of a terrorist attack being carried out by Isis forces at or around Kabul’s Hamid Karzai International Airport.

       Speaking with CNN’s Brianna Keilar, Jake Sullivan confirmed that the US was working to safely transport Americans and others to the airport where evacuations are being managed by the US military while guarding against the danger presented by militants allied with the group.

       “The threat [of an attack] is real. It’s acute. It is persistent. And it is something we’re focused on with every tool in our arsenal,” said Mr Sullivan.

       “It is something that we are placing paramount priority on stopping or disrupting, and we’ll do everything we can as long as we’re on the ground to keep that from happening, but we are taking it absolutely deadly seriously,” he continued.

       The White House adviser added that US officials were taking the threat posed by Isis “deadly seriously”. Isis is not allied with the Taliban, whose forces took Kabul and toppled the Afghan government last weekend, and has warred with the rival militant group on numerous occasions.

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       National security adviser Jake Sullivan on the threat of ISIS attacking the airport in Kabul, Afghanistan: "The threat is real. It is acute. It is persistent. And it is something that we are focused on with every tool in our arsenal." https://t.co/XDgiI0kiQU #CNNSOTU pic.twitter.com/Fg9D0MVUmx

       — State of the Union (@CNNSotu) August 22, 2021

       The chaos caused by the Taliban’s assumption of control over every aspect of Afghanistan’s government could present new opportunities for Isis forces to strike at either Taliban forces, Afghan civilians, or Americans remaining in the country.

       Mr Sullivan confirmed on Sunday that “several thousand” Americans remain in Afghanistan as the evacuations unfold; it wasn’t clear how many were clustered in the capital.

       "We are working hard to organise groups of Americans, to bring them on the airbase, to get them on flights and get them out of the country," said Mr Sullivan.

       The White House has faced sharp criticism over the past week for the way the withdrawal from Afghanistan has unfolded amid the Taliban takeover of Kabul; early last week scenes of Afghan civilians clinging to and falling from departing US aircraft shocked many who questioned why the Biden administration had not begun evacuations before the capital fell.

       Many of the administration’s critics, particularly at home, have attacked the manner of the withdrawal while agreeing that ending US involvement in Afghanistan was necessary; others, including many in the UK such as former Prime Minister Tony Blair, have opposed the US pullout entirely and accused America of abandoning its allies in the region.