In the summer of 2011, Army Lt. Gen. William Caldwell IV made a round of public appearances to boast that he had finally solved a problem that had kept U.S. troops bogged down in Afghanistan for a decade. Under his watch, he asserted, U.S. military advisers and trainers had transformed the ragtag Afghan army and police into a professional fighting force that could defend the country and keep the Taliban at bay.

“We’ve made tremendous strides, incredible progress,” Caldwell, the head of the U.S. and NATO training command in Afghanistan, told the Council on Foreign Relations in June 2011. “They’re probably the best-trained, the best-equipped and the best-led of any forces we’ve developed yet inside of Afghanistan. They only continue to get better with time.”

Three months later, in a news briefing at the Pentagon, Caldwell said the Afghan soldiers and police previously had been in terrible shape: poorly led, uninspired and more than 90 percent of them illiterate. But he said the Obama administration’s decision to spend $6 billion a year to train and equip the Afghan security forces had produced a remarkable turnaround. He predicted that the Taliban-led insurgency would subside and that the Afghans would take over responsibility for securing their country by the end of 2014, enabling U.S. combat troops to leave.

“It really does give you a lot of hope for the future of what this country may have ahead of itself,” he said.

In fact, according to documents obtained for the forthcoming Washington Post book“The Afghanistan Papers: A Secret History of the War,” U.S. military officials privately harbored fundamental doubts for the duration of the war that the Afghan security forces could ever become competent or shed their dependency on U.S. money and firepower. “Thinking we could build the military that fast and that well was insane,” an unnamed former U.S. official told government interviewers in 2016.