The Taliban not only routed Afghanistan's army but also seized a trove of their foe's expensive American weapons, the White House confirmed Tuesday. 

"We don't have a complete picture, obviously, of where every article of defense materials has gone, but certainly, a fair amount of it has fallen into the hands of the Taliban, and obviously, we don't have a sense that they are going to readily hand it over to us at the airport," White House national security adviser Jake Sullivan told reporters at a briefing in Washington.

As they swept across the mountainous Asian country in the past week, the Taliban picked up an assortment of weapons that the United States supplied to Afghan forces, including guns, ammunition and vaunted Black Hawk helicopters.

Depending on the model, the Black Hawks, manufactured by Sikorsky Aircraft in Connecticut, cost from about $6 million to $10 million apiece.

"Those Black Hawks were not given to the Taliban. They were given to the Afghan national security forces to be able to defend themselves at the specific request (of) President Ghani, who came to the Oval Office and asked for additional air capability, among other things," Sullivan said.

In an Aug 15 tweet by World on Alert, Taliban members were photographed standing in front of a Brazilian-made Embraer A-29 attack plane, modified by American defense contractor Sierra Nevada, and an MD-530F utility helicopter produced by MD Helicopters in Arizona.

Bradley Bowman, a former Black Hawk pilot who served in Afghanistan and a critic of the US pullout from the landlocked country, told Defense News "there's no doubt that they've captured hundreds of Humvees and artillery and other equipment — and aircraft".

"This should be deeply, deeply troubling to Americans, not only because we help fund those and provide those, but because how the Taliban could benefit," he added.

"It's understandable for people to be concerned about any capability falling into the hands of folks where we don't know exactly how they're going to use it, who they are going to use it against, whether that's an M16 (rifle) or whether that's an A-29," General Mark Kelly, who leads Air Combat Command, told Defense News in an Aug 16 interview.

"But suffice to say that the technology that's in the A-29 is not cutting-edge technology," he added. "When you look at the airplane's range and speed and computer power and lifting capability … it's not something that, frankly, concerns us."

The Afghan air force operated 211 aircraft, with about 167 planes and helicopters available as of June 30, according to a recent report by the US Special Inspector General for Afghanistan Reconstruction (SIGAR), a congressional watchdog that has kept tabs on US operations in Afghanistan since 2008.

The $83 billion invested in Afghan forces over 20 years is nearly double last year's budget for the US Marine Corps and is slightly more than what Congress budgeted last year for food stamps for about 40 million Americans, according to The Associated Press.

One section of the comprehensive 140-page SIGAR report of August 2021, titled, What We Need to Learn: Lessons Learned From 20 Years of Afghanistan Reconstruction said: "Many mistakes were borne from a willful disregard for information that may have been available. After all, in many cases, the US government's very purpose was to usher in an orderly revolution that would replace existing Afghan social systems with Western or 'modern' systems.

"If the intention was to build institutions from scratch, understanding and working within the country's traditional systems was unnecessary. As one former senior USAID official told SIGAR, 'We wanted to give them something they had never had before,'" the report said.  

In other Afghanistan news, US evacuation flights resumed after a halt Monday, when thousands of people rushed the airport in a desperate attempt to flee the country.

On Tuesday, the Taliban entered the civilian half of the airport, firing rounds into the air to move out around 500 people there, said an Afghan official who spoke on condition of anonymity.

The US Embassy in Kabul, which set up on the military side of the airport, urged Americans to register online to be evacuated but not to come to the airport before being contacted.

The State Department said it was sending John Bass, a former ambassador to Afghanistan, to manage the evacuations in Kabul. The Pentagon said Army Major General Christopher Donohue, commander of the 82nd Airborne Division, will direct airport security operations.

Pentagon spokesman John Kirby said that US officers were speaking with Taliban commanders "multiple times a day" to avoid conflict at the airport.

US President Joe Biden has said he wants the evacuation completed by Aug 31.

Sullivan declined to say whether that deadline would be met. 

White House press secretary Jen Psaki would not commit Tuesday to getting 11,000 Americans out of Afghanistan if they were still there Aug 31. 

"Can you offer any guarantee to Americans and Afghan allies that if they remain there past the end of month us troops will help them evacuate?" a reporter asked.

"Our focus right now is on doing the work at hand, the task at hand. That is day by day getting as many American citizens, as many SIV (special immigrant visa) applicants, as many members of the vulnerable population who are eligible to be evacuated to the airport and out on planes," she said.

The State Department has received more than 80,000 visa applications for Afghans who worked with the US government or are at risk, The Washington Post reported.

Psaki said there were 11,000 "self-identified" Americans in Afghanistan, but more may come forward to request assistance. 

Earlier on Tuesday, Kirby had said there are between 5,000 and 10,000 still there.  

On Monday, the US evacuated 700 people, including 150 Americans. The Pentagon is looking to evacuate between 5,000 and 9,000 people daily for the next two weeks.

The Taliban vowed Tuesday to respect women's rights, forgive the people who fought against them and ensure that the country does not provide cover for terrorists. Talks also continued Tuesday between the Taliban and several Afghan politicians, including former president Hamid Karzai, and Abdullah Abdullah, who once led the country's negotiating council. The Taliban have said they want to form an "inclusive, Islamic government".

The Associated Press contributed to this story.