Billions of dollars of U.S. weapons are now in the hands of the Taliban following the quick collapse of Afghan security forces that were trained to use the military equipment.

Among the items seized by the Taliban are Black Hawk helicopters and A-29 Super Tucano attack aircraft.

Photos have also circulated of Taliban fighters clutching U.S.-made M4 carbines and M16 rifles instead of their iconic AK-47s. And the militants have been spotted with U.S. humvees and mine-resistant ambush protected vehicles.

While it’s virtually impossible to operate advanced aircraft without training, seizing the hardware gives the militants a propaganda boost and underscores the amount of wasted funds on U.S. military efforts in Afghanistan over the last 20 years.

“When an armed group gets their hands on American-made weaponry, it’s sort of a status symbol. It’s a psychological win,” said Elias Yousif, deputy director of the Center for International Policy’s Security Assistance Monitor.

“Clearly, this is an indictment of the U.S. security cooperation enterprise broadly,” he added. “It really should raise a lot of concerns about what is the wider enterprise that is going on every single day, whether that’s in the Middle East, Sub-Saharan Africa, East Asia.”

The United States spent an estimated $83 billion training and equipping Afghan security forces over the last two decades.

Between 2003 and 2016, the United States transferred 75,898 vehicles, 599,690 weapons, 162,643 pieces of communications equipment, 208 aircraft, and 16,191 pieces of intelligence, surveillance and reconnaissance equipment to the Afghan forces, according to a 2017 Government Accountability Office report.

From 2017 to 2019, the United States also gave Afghan forces 7,035 machine guns, 4,702 Humvees, 20,040 hand grenades, 2,520 bombs and 1,394 grenade launchers, among other equipment, according to a report last year from the Special Inspector General for Afghanistan Reconstruction (SIGAR).

As of June 30, Afghan forces had 211 U.S.-supplied aircraft in their inventory, a separate SIGAR report said.

At least 46 of those aircraft are now in Uzbekistan after more than 500 Afghan troops used them to flee as the government in Kabul collapsed over the weekend.

It is unclear exactly how many weapons have fallen into the hands of the Taliban, but the Biden administration has acknowledged it’s a “fair amount.”

“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,” White House national security adviser Jake Sullivan said Tuesday. “And obviously, we don’t have a sense that they are going to readily hand it over to us at the airport.”

Still, Sullivan defended President Biden’s decision-making in leaving the Afghan forces with high-end equipment.

Even as the U.S. military was withdrawing from Afghanistan, the United States kept aircraft flowing to the Afghans, in July touting plans to send 35 Black Hawk helicopters and three A-29s.

“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 [Afghan] President [Ashraf] Ghani, who came to the Oval Office and asked for additional air capability, among other things,” Sullivan said.

“So, the president had a choice. He could not give it to them with the risk that it would fall into the Taliban’s hands eventually, or he could give it to them with the hope that they could deploy it in service of defending their country,” Sullivan continued. “Both of those options had risks. He had to choose. And he made a choice.”

Pentagon press secretary John Kirby on Wednesday also held there was a “very deliberate” process as U.S. forces withdrew in deciding what equipment to destroy, give to Afghan forces or redeploy elsewhere in the Middle East.

While the Taliban may be “keen” to use some of the more advanced U.S. weaponry, including the aircraft, the militants likely would not be able to keep them in the air for long even if they could coax former Afghans pilot into flying for them, said Yousif of the Center for International Policy.

“They may be able to manage a flight or two or to operate them in some really limited capacity in the short term, but without long term sustainment, maintenance, servicing, that sort of thing, it wouldn’t turn into a robust or useful military capability,” he said. “It took the Afghans and the United States a long time to develop an indigenous air capability, and even then, they were reliant on the United States to keep those planes in the sky.”

A more immediate concern, Yousif said, is that so many small arms were left behind.

“They are easy to maintain, easy to learn how to use, easy to transport,” he said. “The concern for all small arms is that they are durable goods and they can be transferred, sold. We’ve seen this before where a conflict ends and the arms that stay there make their way to all parts of the world.”

On Wednesday, more than two dozen Republican senators demanded a “full accounting” of U.S. military equipment given to Afghan forces over the past 12 months, what’s been seized by the Taliban and what plans there are to either recapture or destroy the equipment.

“As we watched the images coming out of Afghanistan as the Taliban retook the country, we were horrified to see U.S. equipment – including UH-60 Black Hawks – in the hands of the Taliban,” the 25 senators, led by Sen. Marco Rubio (Fla.), wrote in a letter to Defense Secretary Lloyd Austin.

“It is unconscionable that high-tech military equipment paid for by U.S. taxpayers has fallen into the hands of the Taliban and their terrorist allies,” they added. “Securing U.S. assets should have been among the top priorities for the U.S. Department of Defense prior to announcing the withdrawal from Afghanistan.”

Chairman of the Joint Chiefs of Staff Gen. Mark Milley on Wednesday declined to comment on the possibility of destroying equipment, saying the military’s focus right now is on evacuation operations. Still, Milley told reporters that “we obviously have capabilities.”

“We don’t obviously want to see our equipment in the hands of those who would act against our interest or the interest of the Afghan people and increase violence and insecurity inside Afghanistan,” Kirby said in his own briefing. “There are numerous policy choices that can be made, up to and including destruction, and what I would tell you at this point is those decisions about disposition of that level of equipment in Afghanistan haven’t been made yet.”