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.