WASHINGTON (AP) — The U.S. military airlift of Americans and others from Kabul will continue until the final hours of President Joe Biden's Aug. 31 deadline for ending the frantic evacuation from Taliban-controlled Afghanistan, Pentagon officials said Wednesday.

John Kirby, the chief Pentagon spokesman, said more than 4,400 American citizens have been evacuated thus far, an increase of about 400 from Tuesday. More than 80,000 people, mostly Afghans, have been airlifted since Aug. 14, he said.

Secretary of State Antony Blinken was to elaborate later Wednesday on details of the evacuation of Americans. The State Department has not publicly said how many Americans it believes are still hoping to leave.

Kirby said the U.S. military will preserve as much military airlift capacity at the Kabul airport as possible in the coming days. The military will "continue to evacuate needed populations all the way to the end," he said. He added that in the final days and hours there will have to be a balance in getting out evacuees as well as U.S. troops and their equipment.

The number of U.S. troops at the airport has dropped by about 400, he said, to 5,400, but the final withdrawal has not yet begun.

Kirby said that in coming days, Defense Secretary Lloyd Austin will consult directly with Gen. Frank McKenzie, the head of Central Command and overseer of the evacuation operation, before McKenzie moves ahead with the final withdrawal.

Biden said Tuesday that although he is sticking with his self-imposed Aug. 31 deadline for ending the evacuation, he has asked Austin and Blinken to provide him with contingency plans in the event that timeline needs to be adjusted.