US Secretary of State Antony Blinken said Tuesday that the Taliban were making good on promises to let out Afghans as he heard firsthand concerns on the country's future during a trip to Qatar.

Blinken met Afghan evacuees and US teams processing them on a two-day visit to Qatar, the transit point for nearly half of the more than 120,000 people airlifted from Afghanistan since the Taliban's lightning takeover on August 15.

President Joe Biden has faced mounting pressure from activists and Republican rivals who say the Taliban have been preventing several hundred people, including Americans, from flying out of the northern city of Mazar-i-Sharif on charter flights scheduled over the past week.

But Blinken said the United States had been in touch again Tuesday with the Taliban who promised to let Afghans "freely depart" -- a key test as the United States weighs whether to work with a future government in Afghanistan led by the Islamists.

"We are not aware of anyone being held on an aircraft or any hostage-like situation in Mazar-i-Sharif," Blinken told a news conference in Doha where he and Defense Secretary Lloyd Austin met their Qatari opposite numbers.

"We have been assured, again, that all American citizens and Afghan citizens with valid travel documents will be allowed to leave," Blinken said. "We intend to hold the Taliban to that."

He said the United States was seeking to resolve problems with charter flights including security screening and some passengers' lack of identification.

He said the Taliban cooperated Monday when a family of four US citizens left overland, the first such departure arranged by the US government after the chaotic end to the 20-year US war.

Qatar told Blinken it was moving quickly with Turkey to restore the ramshackle Kabul airport, a move that would allow more people to leave and humanitarian supplies to come in.

Concerns for future 

Blinken and Austin voiced appreciation to Qatar's ruler, Emir Sheikh Tamim bin Hamad Al-Thani, and toured the Al Udeid military air base outside Doha which became the busiest point of entry for evacuated Afghans.

In an aircraft hangar ventilated to protect from the searing desert heat, Blinken walked past some 200 green cots -- now empty as Afghans moved out -- and tables where US troops distributed water, baby formula and nappies.

He later met members of the Afghan girls' robotics team, who became icons of progress in a country where the former Taliban regime from 1996-2001 vigorously banned female education as part of an austere interpretation of Islam.

The some 20 high school girls have since dispersed around the world including in Mexico and Qatar, which on Tuesday granted them scholarships.

Roya Mahboob, an entrepreneur who backed the so-called "Afghan Dreamers," voiced appreciation for the evacuations but worried about thousands of other students and teachers still in Afghanistan.

"I think everybody is scared about the future of Afghanistan," she told Blinken.

He voiced empathy but acknowledged questions remain after Biden pulled troops out of Afghanistan.

"There's so much change happening. I can't tell you where everything is going to land," Blinken told her.

He said that the United States was committed to girls' education and to helping Afghan refugees.

"We're also committed to doing everything we can to help people who are still in Afghanistan and are looking for a different future.

"That will play out in many different ways in the weeks ahead, the months ahead and maybe even the years ahead," said Blinken, the stepson of a Holocaust survivor who has long been an advocate for refugees.

You literally saved lives

Biden argued the United States could achieve nothing else from its longest war after holding accountable Al-Qaeda over the September 11 attacks 20 years ago this week.

Austin acknowledged the withdrawal affected US capacities on counterterrorism.

"There is no question it will make it more difficult to identify and engage threats that emanate from the region," Austin said of the pullout.

Austin and Blinken spent much of their time saluting US military and civilian forces who handled one of the largest airlifts in history.

"You've helped more people in the past few weeks than most of us will ever get to do in a lifetime. You have literally saved lives," Blinken said.