The Biden administration was taken by surprise by the Taliban’s swift victory in Afghanistan, but according to the head of the watchdog agency who has been reporting on the situation on the ground for years, none of this should have come as a shock.

John Sopko, the Special Inspector General for Afghanistan Reconstruction (SIGAR), told NPR Sunday that the signs have been there for nearly a decade.

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"No. It's not surprising. I mean, we've been warning – my little agency – for the last almost 10 years about issues with the ANDSF, that's the Afghan security forces' capabilities and sustainment," Sopko said. "All the signs have been there."

Sopko pointed to how he himself has testified "50 or 60 times about this" and how SIGAR had released multiple reports going back to 2012 "about changing metrics … ghost soldiers who didn't exist, about poor logistics, about the fact that the Afghans couldn't sustain what we were giving them."

"So it’s been out there," Sopko added.

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National security adviser Jake Sullivan, meanwhile, told ABC’s "Good Morning America" on Monday that developments in Afghanistan took place "at unexpected speed" and that President Biden "thought the Afghan National Security Forces could step up in fight" given the resources the U.S. provided.

Sopko did acknowledge on Sunday that "the speed maybe is a little bit of a surprise," but that "the fact that the ANDSF could not fight on their own should not have been a surprise to anyone."

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SIGAR will release its final report on Tuesday, and Sopko said it provides much to learn in terms of lessons that can be applied in other parts of the world where the U.S. is "doing similar work."

"I think everyone should read that report so we don't repeat the mistakes of the last 20 years," he said.