For Afghans who worked alongside the U.S. who wanted to leave but weren't able to get out, the U.S. would continue to try to help them, Secretary of State Antony Blinken said in remarks Monday evening.

"Our commitment to them has no deadline," he said.

To that end, he thanked Qatar and Turkey for trying to make the Kabul airport operational soon, allowing safe passage to these people.

"This would enable a small number of daily charter flights, which is a key for anyone who wants to depart from Afghanistan moving forward," Blinken said. "We're also working to identify ways to support Americans, legal permanent residents and Afghans who have worked with us to depart via land routes."

But he tempered expectations.

"We have no illusion that any of this will be easy," Blinken said. "Or rapid. This will be an entirely different phase from the evacuation that just concluded. It will take time to work through a new set of challenges."

The secretary of state said the State Department believes there is "still a small number of Americans -- under 200, and likely closer to 100 -- who remain in Afghanistan and want to leave."

"We're trying to determine exactly how many," Secretary Antony Blinken said. "We're going through manifests and calling and texting through our lists. And we'll have more details to share as soon as possible."

But it's difficult to come to a precise number because there are longtime residents of Afghanistan who also hold American passports and have been deciding whether they wanted to leave the country, he added.

"Many are dual-citizen Americans with deep roots and expanded families in Afghanistan who resided there for many years," the secretary said. "For many it's a painful choice."

Even for those who have said they want to stay, the U.S. would still work to get them out if they changed their minds.

"If an American in Afghanistan tells us that they want to stay for now, and then in a week or a month or a year, they reach out and say I've changed my mind, we will help them leave," Blinken said.

Secretary of State Antony Blinken announced that America's diplomatic operations have been transferred from Kabul to Doha, Qatar.

"Given the uncertain security environment and political situation in Afghanistan, it was the prudent step to take," Blinken said. "And let me take this opportunity to thank our outstanding ... Ambassador Ross Wilson who came out of retirement in January 2020 to lead our embassy in Afghanistan and done exceptional courageous work during a highly challenging time."

Blinken said Wilson will depart and his deputy Ian McCary will take over as the top U.S. diplomat, known as the charge d'affaires. Blinken added, "no one is better prepared" for the role.

He said the U.S., for the time being, will use this post in Doha to manage its diplomacy with Afghanistan.

Ambassador John Bass -- the former U.S. ambassador to Afghanistan who returned to Kabul to oversee the evacuation operation -- will lead an ongoing effort to get Americans, Afghans, and other foreigners out of Afghanistan in the weeks to come.

"We will continue our relentless efforts to help Americans, foreign nationals and Afghans leave Afghanistan if they choose," Blinken said.

After the last U.S. military aircraft took off from the airport in Kabul there were celebrations on the ground -- including gunfire.

"The last American occupier withdrew from (Kabul Airport) at 12 o'clock and our country gained its full independence, praise and gratitude be to God," the Taliban spokesman tweeted, according to a translation. "The sounds of gunfire in Kabul are shots of joy at the withdrawal of US troops, and citizens are not worried.‎ We are in the process of overcoming it."