WASHINGTON (AP) — The U.S. military does not have the forces and firepower in Afghanistan to expand its current mission from securing the Kabul airport to collecting Americans and at-risk Afghans elsewhere in the capital and escorting them for evacuation, Defense Secretary Lloyd Austin said Wednesday.

The question of whether those seeking to leave the country before President Joe Biden's Aug. 31 deadline should be rescued and brought to the airport has arisen amid reports that Taliban checkpoints have stopped some designated evacuees.

“I don't have the capability to go out and extend operations currently into Kabul,” Austin said. “And where do you take that? How far do you extend into Kabul, and how long does it take to flow those forces in to be able to do that?”

Austin, a retired four-star Army general who commanded forces in Afghanistan, spoke at his first Pentagon news conference since the Taliban swept to power in Kabul on Sunday.

He said he was mainly focused on the airport, which faced “a number of threats” that must be monitored.

“We cannot afford to either not defend that airfield or not have an airfield that's secure, where we have hundreds or thousands of civilians that can access the airfield,” he said, adding that talks with the Taliban were continuing to ensure safe passage for those evacuating.

Austin said there were about 4,500 U.S. troops at the airport, maintaining security to enable the State Department-run evacuation operation that has been marked by degrees of chaos and confusion. He said the State Department was dispatching more consular affairs officers to speed up the processing of evacuees.

“We're not close to where we want to be” in terms of the pace of the airlift, Austin said.

Senior U.S. military officers were talking to Taliban commanders in Kabul about checkpoints and curfews that have limited the number of Americans and Afghans able to enter the airport. Those U.S. officers included Navy Rear Adm. Peter Vasely, said John Kirby, the chief Pentagon spokesman.

Kirby said that over 24 hours about 2,000 people, including 325 American citizens, had left aboard 18 flights by U.S. Air Force C-17 transport planes. The number of departing Air Force flights was likely to be similar in the coming 24 hours, Kirby said, although he said he could not estimate how many people they would carry.

"Military flights are arriving and departing consistently and there is limited commercial flight operations, as well as some foreign contracted flights that are coming and going,” Kirby said.

The spokesman said the Biden administration was considering its options for dealing with a separate but related problem — the abandonment by Afghan security forces of an array of military equipment, weapons and aircraft that have fallen into the hands of the Taliban or other militant groups.

“We don't, obviously, want to see our equipment in the hands of those who would act against our interests or the interests of the Afghan people and increase violence and insecurity inside Afghanistan,” Kirby said. “There are numerous policy choices that can be made, up to and including destruction.” He said those decisions had not yet been made.

Kirby said several hundred more U.S. troops were expected to arrive at the airport by Thursday.

An Air Force unit arrived overnight that specializes in rapidly setting up and maintaining airfield operations, Kirby said. And he said Marines trained in evacuation support have continued to arrive and will assist in getting civilians onto flights.

Jake Sullivan, Biden's national security adviser. on Tuesday acknowledged reports that some civilians were encountering resistance — “being turned away or pushed back or even beaten” — as they tried to reach the Kabul airport. But he said “very large numbers” were reaching the airport and the problem of the others was being taken up with the Taliban, whose stunningly swift takeover of the country on Sunday plunged the U.S. evacuation effort into chaos, confusion and violence.

The State Department said it was sending John Bass, a former ambassador to Afghanistan, to manage the evacuation operation in Kabul. Army Maj. Gen. Christopher Donohue, a special operations officer and current commander of the 82nd Airborne Division, has arrived to take command of airport security operations.

Kirby disclosed Tuesday that U.S. officers were speaking with Taliban commanders "multiple times a day" about avoiding conflict at the airport. Kirby would not discuss details of the Taliban arrangement, and Sullivan said the question of how much time the Taliban will give the evacuation was still being negotiated.

Gen. Frank McKenzie, head of U.S. Central Command and overall commander of U.S. troops in Kabul, made an unannounced visit to the Afghan capital Tuesday. In a written statement, he said he found that military air traffic controllers and ground handlers were “rapidly scaling up” airlift operations.

McKenzie on Sunday negotiated the safe passage agreement with Taliban leaders in talks held in Doha, Qatar.

On Monday the airlift was temporarily suspended when Afghans desperate to escape the country breeched security and rushed onto the tarmac. Seven people died in several incidents. The Air Force said Tuesday that its Office of Special Investigations was investigating an incident Monday in which a C-17 transport plane taking off was swarmed by desperate Afghan civilians, some of whom died. The Air Force said human remains were found in the plane's wheel well when it landed in Qatar.

Kirby said during television interviews that plans were being made to house up to 22,000 evacuated Afghans and their families at three U.S. Army installations in the continental United States. Those locations are Camp McCoy, Wisconsin; Fort Bliss, Texas, and Fort Lee, Virginia.

___

Associated Press writers Lolita C. Baldor, Darlene Superville, Matthew Lee, Eric Tucker and Mary Clare Jalonick in Washington and Kirsten Grieshaber in Berlin contributed to this report.