The Biden administration failed to realize the Taliban could retake Afghanistan with hardly any fighting

• The Biden admin. has been caught flatfooted by the Taliban's rapid takeover of Afghanistan.
• The Taliban seized major hubs not by fighting, but by making deals with local leaders.
• "The speed with which cities fell was much greater than anyone anticipated," national security advisor Jake Sullivan said.

With less than a month to go until the 20th anniversary of the terror attacks that sparked the US invasion of Afghanistan, the Taliban has regained control of the country. Taliban fighters are now parked outside of the US Embassy in Kabul after a Saigon-esque evacuation that involved diplomats fleeing the building by helicopter. These were not the optics President Joe Biden was hoping for in April when he announced that American troops would be withdrawn from Afghanistan, bringing an end to the longest war in US history.

Just a week ago, the US military assessed it would take up to 90 days for the Taliban to capture the Afghan capital. By Sunday, this assessment was completely discredited as the Taliban entered Kabul.

Indeed, the Biden administration was caught flatfooted by the blistering pace at which the Taliban advanced across Afghanistan in recent days, failing to recognize that the militant Islamist group would face little to no resistance on much of its march toward the capital.

For weeks, President Joe Biden and his top advisors defended the US withdrawal from Afghanistan by citing how well-equipped and trained the Afghan military was. Over and over, the president and others in his administration reiterated that it was up to Afghans to take the fight to the Taliban and prevent the militant Islamist group from returning to power.

In July, Biden expressed "trust" in the capacity of the Afghan military to keep the Taliban at bay, and denied that it was inevitable the militants would once again take over the. country. "The likelihood there's going to be the Taliban overrunning everything and owning the whole country is highly unlikely," Biden said during a July 8 news conference, in words that have aged poorly and been disproven in a matter of weeks.

The administration appears to have severely underestimated how tired Afghans were of fighting, and of the already huge losses borne by its most effective troops.

"The speed with which cities fell was much greater than anyone anticipated," national security advisor Jake Sullivan said Monday during an interview on NBC's "TODAY."

"What the president kept saying over and over again was that it was not inevitable that Kabul would fall, and it wasn't inevitable. There was the capacity to stand up and resist. That capacity did not happen," Sullivan said.

Sullivan said that Afghan forces lacked the "will" to defend their country.

The Taliban gained control of major hubs like Kandahar by striking deals with local leaders involving payoffs or assurances of safe passage, and it captured the city of Jalalabad on Sunday without having to fire a shot.

"There are no clashes taking place right now in Jalalabad because the governor has surrendered to the Taliban," a Jalalabad-based Afghan official said to Reuters. "Allowing passage to the Taliban was the only way to save civilian lives."

Kandahar was taken with "no resistance," a female university student who had to flee the city without her possessions told the Wall Street Journal.

There were clashes with the Taliban in some areas, like heavy fighting with Afghan forces in Helmand province's capital and skirmishes with militants outside Herat in the weeks before its capitulation. Still, the Taliban advance was rapid and its northern victories - such as the surrender of Mazar-i-Sharaf in the north without a fight - allowed them to encircle Kabul, sealing the capital's fate.

The militants also didn't face significant resistance as they entered Kabul, with President Ashraf Ghani fleeing the country and the US-backed government collapsing the same day.

Though Biden expressed faith in the Afghan military, the reality is it's an institution that's been plagued by corruption and discipline issues for years. Afghan forces in many places had not been paid in months, and the Taliban was offering money for them to hand over their weapons, per a Washington Post report.

An Afghan special forces officer also told the Post that the peace deal the Trump administration struck with the Taliban in February 2020 induced a massive level of uncertainty, and Afghan soldiers felt that the US committing to a full withdrawal of troops meant it was only a matter of time before the militants regained control of Afghanistan.

"The day the deal was signed we saw the change. Everyone was just looking out for himself," the officer said. "Some just wanted the money."

The Biden administration maintains that it was the right decision to withdraw troops, however, contending that the president only had bad options moving forward and made the best choice possible in that context.

Biden "stands by" his decision, Sullivan said Monday, stating that the worst-case scenario for the US "would be a circumstance in which we were adding back in thousands and thousands of troops to fight and die in a civil war in Afghanistan when the Afghan army wasn't prepared to fight in it itself."

"What we've learned over the course of the past two weeks is that if we had stayed one more year or two more years or five more years or 10 more years, no amount of training, equipping, or money or lives lost by the United States was going to put the Afghan army in a position to be able to sustain that country on its own," Sullivan added.

But roughly a month ago, Biden was adamant the Afghan military was "better trained, better equipped, and ... more competent in terms of conducting war." It did not take long for Biden to be proven wrong.