Biden says Afghanistan evacuations ‘have a long way to go,’ extends safe-zone around Kabul airport

President Joe Biden said Sunday the U.S.-led evacuation of Americans, at-risk Afghans and others from the Kabul airport picked up speed this weekend, although it remains vulnerable to threats posed by the Islamic State extremist group.

Speaking at the White House, Biden said 11,000 people had been airlifted from Kabul in a 36-hour period this weekend, but he did not provide details. The number appeared to include flights by charter and non-U.S. military aircraft as well as the U.S. Air Force C-17 and C-130 transport planes that have been flying daily from the capital. Tens of thousands of people remain to join the airlift, which has been slowed by security issues and U.S. bureaucracy hurdles.

"But we have a long way to go, and a lot can still go wrong," Biden said.

Biden’s remarks come as the U.S. military continues to work to evacuate Afghans and U.S. personnel from the country amid the takeover. Biden vowed to bring home all Americans and to evacuate Afghans who aided the U.S. war effort.

"Any American who wants to get home will get home," he said. 

The president also said he’s hoping to keep to the August 31 deadline to finish evacuating Americans and allies but said discussions are underway in case the U.S. needs to stay in Afghanistan longer.

But now, potential threats against Americans from the Islamic State group have forced the military to take even greater security precautions. 

Earlier on Sunday, the Pentagon ordered six U.S. commercial airlines to help move evacuees from temporary sites outside of Afghanistan, and the military is said to be considering other "creative ways" to complete evacuations. 

U.S. military planes have been executing corkscrew landings, and other aircraft have fired flares upon takeoff, measures used to prevent missile attacks.

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Kabul's airport, now one of the few ways out of the country for the millions in the city, has seen days of chaos since the Taliban entered the capital on Aug. 15. 

The U.S. military took control of the airport for evacuations a week ago as the capital fell to the Taliban. But Taliban forces controlling the streets around the airport, and the crowds of people gathering outside in hope of escape, have made it difficult and dangerous for foreigners and their Afghan allies to get through.

Biden's national security adviser, Jake Sullivan, said on CNN's "State of the Union" that 3,900 people had been airlifted out of Kabul on U.S. military flights over the past 24 hours. A U.S. defense official, speaking on condition of anonymity to provide details not yet made public, said those people were flown on a total of 23 flights — 14 by C-17 transports and nine aboard C-130 cargo planes.

That represents an increase from 1,600 flown out aboard U.S. military planes in the previous 24 hours but remains far below the 5,000 to 9,000 that the military says it has the capacity to airlift daily. Sullivan also said about 3,900 people were airlifted on non-U.S. military flights over the past 24 hours.

The Biden administration has given no firm estimate of the number of Americans seeking to leave Afghanistan. Some have put the total between 10,000 and 15.000. Sullivan on Sunday put it at "several thousand."

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Republicans in Congress stepped up their criticism of Biden's response and called for the addition of U.S. troops to help Americans get safely to the airport so they can leave.

The U.S. Embassy, which has relocated to the military side of the airport, has told American citizens and others not to come to the airport until they receive precise instructions.

Meanwhile, the Taliban have sought to project a more moderate image than when they last ruled the country, from 1996 until the U.S.-led invasion following the 9/11 attacks, which al-Qaida carried out while being sheltered by the Taliban. 

During their earlier rule, women were largely confined to their homes, television and music were banned, and public executions were held — all in accordance with the Taliban's harsh version of Islamic rule.

This time, the Taliban are holding talks with Afghan officials from previous governments on a political transition and say they will restore peace and security after decades of war. 

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Afghan officials familiar with the talks say the Taliban have said they will not announce a government until after the Aug. 31 deadline for the U.S. troop withdrawal.

Defense Secretary Lloyd Austin told ABC's "This Week" that as Biden's deadline for ending the evacuation operation approaches, he will recommend whether to give it more time.

The Associated Press contributed to this report.