The Taliban's takeover of Afghanistan is a "failure of the international community", Britain's Defence Secretary Ben Wallace said on Monday, assessing that the West's intervention was a job only half-done.
"All of us know that Afghanistan is not finished. It's an unfinished problem for the world and the world needs to help it," he told BBC television.
The former British Army officer last week said US President Joe Biden's predecessor Donald Trump had secured a "rotten deal" with the Islamist militants that allowed their return.
He maintained the 20-year intervention by US-led forces in Afghanistan "wasn't a waste, it wasn't for nothing" but accused Western powers of being short-sighted in policy matters.
"If it's a failure, it's a failure of the international community to not realise that you don't fix things overnight," he said.
"I'm afraid when you deal with a country like Afghanistan, that is 1,000 years of history effectively and civil war, you manage its problems and you might have to manage it for 100 years.
"It's not something that you just rock in, rock out and expect something to be fixed."
Wallace also said there had been "a failure to recognise that military might on its own" could not completely resolve the situation in Afghanistan.
"Half the mission on its own... was entirely successful," he said, pointing to the removal of the Taliban after the September 11, 2001 attacks and the death of Al-Qaeda chief Osama bin Laden, which made the world safer.
But "that doesn't mean that the next 20 years are going to be the same", he added, echoing concerns about the impact of the hardline group's resurgence on world security.
Britain last month withdrew the majority of its 750 remaining troops in Afghanistan, but last week announced that 600 soldiers would return to help with repatriation.
Wallace told Sky News 370 embassy staff and British citizens were flown out on Saturday and Sunday, with 782 Afghans scheduled to leave in the next 24 to 36 hours.
Officials are aiming to evacuate 1,200 to 1,500 people from Afghanistan a day, he added.
Prime Minister Boris Johnson has said Britain would help some 3,000 nationals to leave.
Senior politicians and military top brass have strongly criticised the withdrawal of international troops from Afghanistan.
Parliament has been recalled on Wednesday to discuss the situation, including asylum and support for Afghan nationals who have fled.