A former Chief of the General Staff has told Forces News that Afghanistan is facing the prospect of a civil war as Western troops near the completion of their withdrawal from the country.
"It's really down to the will of the people, the will of the Afghan Security forces, whether they want to control sufficient of their country for a majority of their people, particularly in the urban areas, to live the kind of life that we've shown them the possibility of," Lord Dannatt said.
The US began withdrawing troops from the country on 1 May and has a deadline currently set for 11 September for a complete troop drawdown.
Earlier this week, the last German and Italian troops arrived back in their respective countries – 20 years after the first Western soldiers were deployed.
Lord Dannatt told Forces News it is "not a great situation" in Afghanistan.
"The Taliban has risen in strength," he said. "It's captured district after district in the rural areas and is making a lot of unwanted progress as international forces have drawn down.
"And, sadly, although we've invested many billions of pounds and efforts and time into the Afghan National Army, it's not proving as effective as we'd hoped it would."
Watch: Timeline of British forces in Afghanistan.
However, Lord Dannatt added it is "not all bad news".
"Although the Taliban's making great progress in the rural areas, in the provincial centres, somewhere like Kandahar, for example, and, of course, in the national capital Kabul, they're not making the progress that they would like to have done," he said.
"But, given that the international community, led by the Americans, have decided 'we're going', the Taliban is seizing its opportunity.
"And, frankly, is now ignoring a peace process through the talks that they were only paying lip service to in Doha."
He added that "international support for Afghanistan is going to be diplomatic, it's going to be economic and it's going to be delivered in ways that are non-military".
"Soft power as opposed to hard power," he said.
Lord Dannatt said the UK's presence in Afghanistan "has been costly" but has neither been "a total failure" or "the success that we perhaps had in mind".
"So we have to wait and see what happens," he said.
"It does then beg the wider question as to... whether the campaign has been worth it."