WASHINGTON — Nearly 20 years after invading Afghanistan to oust the Taliban and hunt down al-Qaida, the U.S. military has vacated its biggest airfield in the country, advancing a final withdrawal that the Pentagon on Friday said will be completed by the end of August.

President Joe Biden had instructed the Pentagon to complete the military withdrawal by Sept. 11, the 20th anniversary of the terrorist attacks on the United States, but the Pentagon now says it can finish the drawdown a little earlier. In fact, the drawdown is already largely completed, and officials had said it could be wrapped up this weekend.

But a number of related issues need to be worked out in coming weeks, including a new U.S. military command structure in Kabul and talks with Turkey on an arrangement for maintaining security at the Kabul airport, so an official end to the pullout will not be announced soon.

“A safe, orderly drawdown enables us to maintain an ongoing diplomatic presence, support the Afghan people and the government, and prevent Afghanistan from once again becoming a safe haven for terrorists that threatens our homeland,” Pentagon press secretary John Kirby said.

The administration is narrowing options for ensuring the safety of thousands of Afghans whose applications for special visas to the U.S. have yet to be approved. The administration has said it’s willing to evacuate them to third countries pending their visa approvals but has yet to determine where. Officials said Friday that one possibility is to relocate them to neighboring countries in Central Asia where they could be protected from possible retaliation.

The White House and State Department have declined to comment on the numbers to be relocated or where they might go, but the foreign ministers of Tajikistan and Uzbekistan were both in Washington this week, and the subject of Afghan security was raised in meetings they held with Secretary of State Antony Blinken and Defense Secretary Lloyd Austin.

Mr. Kirby said that Mr. Austin on Friday approved a new command structure in Afghanistan to transition the U.S. military mission from warfighting to two new objectives — protecting a continuing U.S. diplomatic presence in Kabul and maintaining liaison with the Afghan military.

A satellite military office based in Qatar will be established to administer U.S. financial support for the Afghan military and police.

The Taliban welcomed the American withdrawal from Bagram Airfield. Taliban spokesman Zabihullah Mujahid tweeted that the departure was a “positive step,” urging for the “withdrawal of foreign forces from all parts of the country.”

First Published: July 3, 2021, 4:00 a.m.