The head of the UK armed forces has admitted that everybody including the Taliban got it wrong about how quickly the group would take over Kabul.
Gen Nick Carter said intelligence assessments had suggested that the capital would fall this year despite claims by Foreign Secretary Dominic Raab that briefings indicated this was unlikely.
Prime Minister Boris Johnson and Mr Raab, who was on holiday in Greece when the Taliban toppled Kabul, have face criticism for their handling of the situation and the failure to fly hundreds of vulnerable Afghans out of the country.
Mr Raab has spoken of intelligence shortcomings and told MPs last week that the “central assessment” was a “steady deterioration” after US troops left the country in August.
Gen Carter, the Chief of the Defence Staff, said intelligence suggested it was “entirely possible” that the Afghan government would not be able to hold out for long in the face of the Taliban advance.
“Many of the assessments suggested it wouldn't last the course of the year and, of course, that's proven to be correct,” he said.
He said that in July there were a number of scenarios and “one of them certainly would be a collapse and state fracture”.
“I think everybody got it wrong,” he told the BBC. “It was the pace of it that surprised us and I don't think we realised quite what the Taliban were up to."
“They weren't really fighting for the cities they eventually captured, they were negotiating for them, and I think you'll find a lot of money changed hands as they managed to buy off those who might have fought for them.”
He said the Taliban had not expected to take power so quickly as the US pulled its troops out of Afghanistan.
The rapid advance led to evacuation chaos. More than 8,000 former Afghan staff and their family members were among the 15,000-plus people flown to safety by the UK since August 13. But up to 1,100 people deemed eligible for help were left behind.
“At the moment they suffer from what we military call catastrophic success,” Gen Carter said. “They were not expecting to be in government as quickly as they have appeared and the reality is they are trying to find their feet.
“We need to wait to see how this happens and recognise that they're probably going to need a bit of help in order to run a modern state effectively and if they behave perhaps they will get some help.”