President Joe Biden said Wednesday that US troops won't leave any Americans behind in Afghanistan even if it means staying in Kabul beyond the August 31 deadline that has been agreed upon.

In his first interview since the Taliban captured the Afghan capital in a lightning offensive, Biden told ABC News that "chaos" had been unavoidable.

US leaders have said they are sticking to an August 31 deadline for flying out the last troops.

However, Biden said for the first time that US soldiers could stay longer if any Americans were still left behind. "If there are American citizens left, we're going to stay to get them all out," Biden explained.

US troops are still flying in to secure the Kabul airport and organize evacuations. While initially 3,000 troops were sanctioned for the task the number has now been doubled to 6,000 following the sudden collapse of the Afghan army and the resultant chaos on the ground. US forces have also been put on standby in nearby Kuwait and can be quickly deployed if the need arises. 

Also read: Biden’s bid to evacuate 22,000 at-risk Afghans faces Taliban barrier

The Taliban militants have complete control over the rest of the city and decide who will be allowed to get to the US-controlled Kabul airport.

Speaking about the chaos amid which the frantic evacuations are taking place, Biden told ABC News there was never going to be an easy exit.

"The idea that somehow, there's a way to have gotten out without chaos ensuing — I don't know how that happens," Biden said.

He added that the Taliban were currently assisting the US forces they'd spent so many years battling — at least in helping foreign nationals to escape.

"They're cooperating, letting American citizens get out, American personnel get out, embassies get out, etcetera," Biden said.

However, "we're having some more difficulty having those who helped us when we were in there" leave, he said, apparently referring to local

Also read: Regional powers drive Afghan diplomacy as Washington’s star fades

In the interview, the president rejected criticisms that his administration had suffered a huge intelligence failure.

Referring to the sudden collapse of the Western-backed Afghan government and army in the face of the advancing Taliban, Biden said he was convinced the already planned US exit had to proceed.

Asked what he'd thought when images emerged of panic-stricken Afghans swarming airplanes and some even falling off the aircraft after take-off, Biden said his reaction was: "We have to gain control of this, we have to move this more quickly. We have to move in a way in which we can take control of that airport. And we did."

President Joe Biden had also promised to evacuate over 20,000 at-risk Afghans who have been working with the U.S. government appears to have run into the Taliban barrier as many of these individuals are facing an uphill task in reaching the airport.

Some of these individuals are still in the provinces and have to go through several Taliban check-points before they can reach Kabul. Many of those who are in Kabul are unable to reach the airport as they cannot get past the gun-toting Taliban fighters who have set up barriers at crucial points.

NATO Secretary General Jens Stoltenberg admitted in an interview on CNN that at-risk Afghans were facing a problem in reaching the Kabul airport. He said that NATO was in touch with the Taliban leadership to allow such individuals to come to the airport.