'That trust was badly broken when we left [Afghanistan] before and it was badly broken in Pakistan ... when we sanctioned them [over their nuclear programme],' he said. 'It's going to take a lot of time to develop.'

'I liken it to somebody who has been starving for a significant period of time and all the sudden you put all the food they need in the world there - they're just not going to come back overnight,' he said.

'What I do see and have seen over the last two or three trips is something that I call a 'culture of poverty' and it isn't just that we've under-resourced it - we've under-resourced it for a significant period of time,' Mullen said.

He said a strategy devised since President Barack Obama took office is intended to reverse these negative trends. 'We now have a strategy which is a civilian-military campaign plan, a civilian-military strategy.'