The former head of the British military has condemned what he said were a series of failures that led to the capture of Afghanistan by the Taliban a year ago.
One year on from the first chaotic morning of Taliban rule, when people flocked to Kabul International Airport in desperate attempts to escape, Gen Sir Nick Carter said there had been too little planning for what might unfold when western troops left Afghanistan.
He told BBC Radio 4's Today programme on Tuesday that the events of last summer were “the symptom of a much wider malaise” that had built up over the 20-year campaign by the American-led coalition in Afghanistan.
“Ultimately, I think it was a series of failures,” he said.
“It was a failure of politics. It was a failure to understand the local political circumstances over a period of 20 years.
"It was a failure to understand that the government that we constructed wasn't sustainable. It was a failure to understand that, from that, the Afghan security forces weren't sustainable.
"Above all, it was a failure of political will.”
The general, who acted as a mediator during talks on Afghanistan last year, said the deal negotiated between the US and the Taliban in 2020 had put more focus on arranging an American exit than on keeping the militants in check.
“I think there was too much assumption that the best case would happen rather than the worst case,” he said.
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But Mr Biden was heavily criticised after the Afghan government and military collapsed before the US had even finished withdrawing its troops.
Britain and other allies said they had little choice but to follow Mr Biden's lead because there was no plausible prospect of them maintaining a military presence in Afghanistan without American firepower.
Gen Carter said the international community should engage with the Taliban to prevent it becoming a “pariah state” that might once again harbour terrorist groups such as Al Qaeda.
He said Taliban leaders, especially those he described as having “a more modernist view on life”, should be persuaded of the merits of engaging with the wider world.
But Gen Carter said any possible relationship had been undermined by the discovery and killing of Al Qaeda chief Ayman Al Zawahiri in Kabul at the end of last month, calling into question Taliban assurances about keeping terrorists at bay.
Former prime minister Gordon Brown urged the Taliban on Tuesday to listen to community leaders and other Muslim countries in order to find a way to educate girls in line with Taliban religious beliefs.
Mr Brown and fellow UN education envoy Yasmine Sherif wrote in a joint article for The Times that the current regime was "condemning Afghanistan to a future as an uneducated pariah state".
"All other Muslim nations recognise knowledge is at the core of Islam, except in Afghanistan, a country that having endured 40 years of conflict and destruction, urgently needs to rebuild," they said.
Another senior figure in the British military, former army chief Lord Richard Dannatt, said on Monday that Britain should increase aid to rescue Afghanistan from a "terrible condition" a year after the Taliban took power.
A UN special representative said the humanitarian situation could best be described as a "pure catastrophe", while the Norwegian Refugee Council spoke of displaced people being concentrated around major cities.
The council's secretary general Jan Egeland told Sky News that the Taliban had gone back on promises made last year to uphold human rights and allow girls to to to school.
"If western diplomats now are only interested in Ukraine and a few other places, and being very nationalistic in their attitude, then we have failed" the women of Afghanistan, he said.