The US presence in Afghanistan is ending with one final miscalculation. The speed with which Afghan forces have capitulated and their government has collapsed has outpaced even the most pessimistic predictions.

Last month, Joe Biden said it is was “highly unlikely” that the Taliban would be “overrunning everything and owning the whole country”. And yet this is exactly what has happened. Taliban fighters are in Kabul. Ashraf Ghani, the Afghan president, has fled the country.

“The Taliban is not the North Vietnamese army. They’re not remotely comparable in terms of capability. There’s going to be no circumstance where you see people being lifted off the roof of the embassy of the United States from Afghanistan,” said Biden only a few weeks ago. Fast-forward to yesterday, when Biden announced that he has had to scramble to deploy 5,000 American troops to help with a hurried and chaotic evacuation. US embassy employees are shredding documents and making a break for the airport.

The total collapse of the Afghan state makes plain the failures of two decades of attempted nation building

On the one hand, the total collapse of the Afghan state and the inability of the country’s security forces to do anything to halt the Taliban make plain the failures of two decades of attempted nation building. The $88 billion that the US has spent on the Afghan army has gone up in smoke, exposing the hubris of successive teams of American policymakers. Much of the weaponry given to the Afghan army is now in the hands of the Taliban.

Biden made this point when he defended his withdrawal on Saturday. “One more year, or five more years, of US military presence would not have made a difference if the Afghan military cannot or will not hold its own country,” he said. “And an endless American presence in the middle of another country’s civil conflict was not acceptable to me.”

But whatever the rights and wrongs of the case for withdrawal, its execution has gone very badly wrong.

At the heart of it all is a military intelligence failure of epic proportions. From the misjudgment of the speed with which the Taliban could take control, much chaos has flowed. A withdrawal plan has been pared back to the most basic of tasks, with America now aiming for little more than the safe evacuation of its citizens. The US was reduced to begging the Taliban to slow its advance on Kabul, arguing that doing so would increase “the likelihood that both the international community and Afghans will accept the Taliban’s entry into the capital”.

America has also been deplorably slow to help Afghan allies for whom staying in the country under the Taliban would amount to a death sentence. One estimate puts the number of Afghans who could need to be evacuated under America’s Special Immigrant Visa scheme at 88,000.

The FT’s Gideon Rachman was surely right to point out that: “If Donald Trump were presiding over the debacle in Afghanistan, the US foreign policy establishment would be loudly condemning the irresponsibility and immorality of American strategy. Since it is Joe Biden in the White House there is instead, largely, an embarrassed silence.”

Anthony Blinken, the Secretary of State, is one of many officials who has attempted to shift blame for the chaotic withdrawal onto the Trump administration. It was the deal Trump struck with the Taliban last year that set a deadline for the retreat. But there’s nothing to suggest the new administration tried to renegotiate the date. After all, the desire for a quick withdrawal has been something Biden shared with his predecessor.

While the events of recent days are a dramatic culmination of the mistakes of successive administrations over the years, the frenzied evacuation belongs to Biden. Exactly how much it will tarnish the President in the eyes of the US public remains to be seen. His decision to withdraw was popular.

And it is very unlikely that he will reverse course. He was unambiguous in a statement on Saturday: “I was the fourth president to preside over an American troop presence in Afghanistan—two Republicans, two Democrats, I would not, and will not, pass this war onto a fifth.”

But the image of Biden, alone in a conference room at Camp David receiving updates on the chaos in Kabul, will stick. It illustrates a low point in his presidency, and when the world looks at the photograph, it will see an aged leader of a declining power that couldn’t even organise a withdrawal properly.