KABUL — Hundreds of Afghan forces surrendered to the Taliban in northern Afghanistan on Wednesday, the military’s most significant single collapse since the withdrawal of U.S. forces triggered a wave of territorial gains for the militants.

After holding out for days at a military base on the edge of Kunduz, an entire Afghan army corps surrendered to Taliban fighters Wednesday morning, handing over valuable equipment — much of it American — according to two Afghan officers who spoke on the condition of anonymity because they were not authorized to speak to the media.

The move essentially ceded the last island of government control in the provincial capital to the Taliban. The group overran much of Kunduz over the weekend, one advance amid days of sweeping gains by the fighters across northern and western Afghanistan. The Taliban has now pushed into nine provincial capitals. On Tuesday alone, three towns were overrun by the group.

“The Taliban are at the gate, but no one is fighting. I don’t understand,” said one of the Afghan officers, recounting the conversation he had with a member of his unit who was at the Kunduz base when the Taliban began to push closer. “Brother, if no one else fights, why should I fight?” was the reply.

"The Afghanistan Papers" author Craig Whitlock explains how presidents misled the public about the war in Afghanistan for nearly two decades. (Joy Yi/The Washington Post)

Moments after the conversation, the soldier changed into civilian clothing and fled into the city, the officer said. That was before he knew a deal had been in the works between the Taliban and some of the base’s commanders.

In the days leading up to the mass surrender in Kunduz, local elders had visited the base near the city’s airport and asked commanders there to surrender to the Taliban, which pledged not to harm them, said Zargul Alemi, a member of the Kunduz provincial council who fled the province before the surrender. Alemi said that after some commanders accepted the surrender deal, along with a fraction of soldiers at the base, the rest of the forces retreated to a nearby mountain range.

Alemi estimated that as many as 2,000 Afghan troops were at the base at the time of the surrender and desertions. The Afghan army corps stationed there — one of seven in the entire country — was responsible for the northern region.

“I don’t know why the commanders did not gather their forces and fight until the last drop of their blood, with all the guns, resources and ammunition they had in the airport and the corps,” Alemi said. The soldiers who surrendered handed over Humvees, weapons and other supplies to the Taliban, she said.

The two Afghan officers said that those who surrendered were escorted by the Taliban to a nearby district, where they were offered protection as long as they did not leave Kunduz province.

Taliban forces are in the midst of a military blitz largely focused in northern and western Afghanistan. On Tuesday, the militants overran the capitals of Badakhshan in the north, Farah in the west and Baghlan, just a five-hour drive north of Kabul.

“We feel betrayed,” said Fawzia Yaftali, another Kunduz provincial council member, who accused the government in Kabul of making a deal with the Taliban to hand the militants control of the country’s north.

One of the Afghan officers blamed sophisticated Taliban psychological operations for much of the collapse of Afghanistan’s military. He said rumors have spread through the Afghan security forces that Kabul has made a deal with the Taliban to hand over control of portions of the country.

The impact on morale has been detrimental, he said. In recent months, desertions have been so common that the number of Afghan military casualties has dropped in half, he said.

“We aren’t loosing our forces in the fight anymore,” the officer said. “They are just changing their clothes and putting their guns down.”

Taliban fighters have expanded their control in southern, western and central Afghanistan and have overrun much of the north since the final phase of the U.S. withdrawal began in May. Initially, the group focused on the country’s rural areas, but over the past week, it has started pushing into urban centers.

Government control has shrunk dramatically, to less than a third of the country’s territory. The United States is continuing to support Afghan forces with airstrikes, but the withdrawal of foreign troops is set to conclude at the end of August.

On Wednesday, Pentagon spokesman John Kirby challenged the view that the U.S. military “fell short over the course of 20 years” in creating a sustainable military in Afghanistan.

“I take exception to the notion that somehow over the course of 20 years we simply failed in trying to improve the competency and capability of Afghan forces when we look at what they’re doing today,” Kirby said. “It comes down to leadership on the battlefield and leadership in Kabul.”

Kirby said that “no one is passing any bucks,” and that Pentagon officials are watching what is happening in Afghanistan with great concern. He declined to address whether the speed of the Taliban’s rise has prompted discussion in the U.S. government about evacuating personnel this month.

According to a U.S. official who spoke on the condition of anonymity because they were not authorized to speak publicly to the media, the Taliban’s simultaneous operations to take provincial capitals are also designed to burn out the two key advantages of Afghan forces — special forces and the Afghan air force.

Afghan attack planes and gunships are flying at a breakneck pace, churning through parts and maintenance needs after the departure of U.S. contractors that maintained the aircraft. The Afghan air force has begun flying aircraft to another country to conduct maintenance, officials have said.

And elite Afghan soldiers were dispatched through the south in key cities such as Lashkar Gah, but in the west and north, where there are far fewer of them, the United States has not been able to use airstrikes at will. For instance, in the southwestern provincial capital of Zaranj, Afghan troops fled mostly without a fight, leaving no one to coordinate a strike on massing Taliban militants, the official said.

Kirby declined to publicly describe recent airstrikes in the closing days of U.S. support from the air.

“We continue to fly airstrikes in support of Afghan forces on the ground, where and when feasible,” Kirby told reporters Monday.

Alex Horton and Dan Lamothe in Washington contributed to this report.

Read more: