The United States has an unwavering commitment to getting US citizens and at-risk Afghans out of Afghanistan, President Joe Biden said, as Taliban fighters beat back thousands desperate to flee outside Kabul airport on Sunday.

Biden said the security situation in Afghanistan was changing rapidly and his administration was under no illusions about the threat from Islamic State militants in Afghanistan known as ISIS-K (for Khorasan).

The Taliban, which seized power in Afghanistan last week as the United States and its allies withdrew troops after a 20-year war, fired in the air and used batons to force people to form queues outside the airport, witnesses said. On Saturday, seven Afghans were killed in a crush at the gates.

A NATO official said at least 20 people had died in the past seven days in and around the airport. Some were shot and others died in stampedes, witnesses have said.

"Let me be clear...