Taking UK and US support out of Afghanistan was "grossly and unbelievable irresponsible", the former UK international development secretary has told the BBC.
The UK and the US have been providing air support to Afghan forces fighting the Taliban - now that line of defence is being removed.
Those aircraft were "a keystone" to their defence and removing them meant "nothing could be held together", Rory Stewart said.
"It's very difficult for an army like the Afghan army to fight without any air support," he said.