The U.S. and its NATO allies propped up the Afghan government and security forces for years, but the moment they withdrew, both crumbled in a matter of weeks.

The stunning collapse of these institutions, which allowed the Taliban to retake Afghanistan, has raised a host of questions about what went wrong after decades of international support.

Some experts contend that persistent and troubling allegations of corruption and abuse surrounding Afghan leaders that were largely ignored by the U.S. and its NATO allies crippled efforts to build a government and military able to withstand the Taliban, gain strong popular support, and meet Afghanistan’s needs.

In a recent New York Times column following the Taliban takeover, Gen. Sami Sadat, a three-star Afghan army general, blamed American politics for the collapse. He also blamed Afghanistan’s leaders, some of whom have been accused of serious corruption and abuse, what he characterized as a “national tragedy” that “rotted our government and military.”

There were generals put in place through connections rather than capability, soldiers in the Afghan security forces that existed only on paper, and supply lines disrupted by officials who siphoned off essential resources. The problems in Afghanistan ran much deeper though, experts said.

Patricia Gossman, a senior Human Rights Watch researcher who has interviewed Afghans and international officials and conducted on-the-ground investigations in Afghanistan, told Insider that problems such as horrific human rights abuses and corruption “definitely undermined” the state’s credibility in Afghan communities and were “a big factor” in the country’s fall.

In Afghanistan, the U.S. and its allies aligned themselves with “some very notorious figures reviled by many communities that they were in because of previous atrocities,” Gossman told Insider, explaining that they also empowered some people that later became problematic while focusing on short-sighted needs.

Ryan Crocker, a career diplomat who served the U.S. as the ambassador to Afghanistan during the Obama administration, once recounted for the Special Inspector General for Afghanistan Reconstruction (SIGAR) a truly uncomfortable encounter with Mohammed Fahim, an Afghan defense minister who later became a vice president.

Fahim giggled as he related to Crocker a story of another senior Afghan minister who had been killed, the ambassador recalled in a conversation obtained as part of The Washington Post’s “Afghanistan Papers.” Later, Crocker revealed, it came out that Fahim might have actually had the official killed.

Crocker explained that he “certainly came out of those opening months with the feeling that even by Afghan standards” he “was in the presence of a totally evil person.”

Afghan leaders within the government, military, and police have been accused of crimes ranging from corruption to murder, rape, torture, and war crimes.

For example, Afghan President Ashraf Ghani’s defense minister Asadullah Khalid, previously the head of the National Directorate of Security, allegedly personally engaged in or ordered torture, sexual violence, and extrajudicial killings, according to Human Rights Watch.

Abdul Rashid Dostum, an Afghan vice president and later a senior Afghan military leader, is accused of war crimes, specifically suffocating enemies in shipping containers, as well as rape, kidnapping, and other human rights abuses.

And Abdul Raziq, a powerful Afghan National Police chief who was killed, was accused of running secret detention centers and carrying out or ordering torture and extrajudicial killings.

‘Choosing the Least Bad Partner’

Experts say that issues at the top exacerbated problems at other levels. “There was this sense that nobody was held accountable for anything,” Gossman said. “You have a trickle-down lack of accountability.”

A U.S. Army veteran of the Afghan war that Insider spoke to recently revealed that he encountered police leaders that expected bribes for information on the Taliban, security checkpoints that had made deals with the Taliban, and some security forces members engaged in child sex trafficking.

Some other veterans had similar experiences. Capt. Dan Quinn, a former U.S. Special Forces soldier, was famously relieved after he beat up a U.S.-backed militia leader sexually abusing a young boy.

“The reason we were here is because we heard the terrible things the Taliban were doing to people, how they were taking away human rights,” Quinn told The New York Times in 2015.

“But,” he added, “we were putting people into power who would do things that were worse than the Taliban did — that was something village elders voiced to me.”

A senior U.S. official reflecting on the situation in Afghanistan in 2015 said that “our money was empowering a lot of bad people,” adding that “there was massive resentment among the Afghan people,” according to The Washington Post’s Afghanistan Papers.

Another U.S. official said that “we were giving out contracts to pretty nasty people, empowering people we shouldn’t have empowered, in order to achieve our own goals.”

“Successive U.S. administrations have largely perceived human rights more as an obstacle than as an essential component of addressing Afghanistan’s problems,” Gossman asserted in a recent Just Security column, adding that “this approach has been catastrophic.”

“It affected the legitimacy of the government,” Gossman, who has spent years documenting human rights abuses in Afghanistan, told Insider. “Maybe it didn’t make people want the Taliban, but they may have seen the Taliban as a better option in certain circumstances.”

Sarah Chayes, who ran non-governmental organizations in Afghanistan and served as a senior advisor to U.S. military leaders in country, told PBS last month that “Afghan government officials would shake people down at every interaction.”

She added that “from Afghans’ perspective, it almost looked like the United States was in favor of this system because our officials were always seen partnering with these venal Afghan leaders.”

Chayes explained that when she was working with the chairman of the Joint Chiefs of Staff in 2011, interagency policy was to ignore high-level corruption and other misdeeds.

“Why would a population take risks to fight the Taliban on behalf of a government that is treating them almost as badly as the Taliban do?” she asked.

That said, not every interaction between the U.S. and NATO and their Afghan partners was necessarily plagued by problems.

“Did we back bad horses across the country? I think probably the answer is no,” Erol Yayboke, a Center for Strategic and International Studies expert and a former international development contractor, told Insider, saying there was likely a mix of both good and bad actors.

“I think the question is less did we back a bad horse and is more were there actual alternatives? What you hear from people who spent years and years working in Afghanistan is that the option was backing people that we had concerns about over corruption, etc., or leaving,” he said.

With U.S. leaders largely against leaving, “we had to find some local partners,” Yayboke said. “I think that a lot of folks that were out there would argue that, in many cases, it was not choosing the best partner. It was choosing the least bad partner.”

“I think that decisions that people were making, including our people in the field, American leaders, were based primarily on least bad options,” he said.

This article was written by Ryan Pickrell and originally published on the Insider.