Signs of progress in Afghanistan are needed within the next two years to convince military coalition partners that success there is possible, Nato's senior civilian representative in the country has said.
Mark Sedwill said both alliance members and the Afghans were "becoming impatient" but insisted the correct strategy and resources were now in place.
He described plans to hand over control of the country to Afghan forces by 2015 as "realistic" and said there were "channels of communication open" between the country's government and elements of the insurgency.
Mr Sedwill told BBC Radio 4's Today programme: "People right through the alliance are impatient, and indeed...the Afghans themselves are becoming impatient.
"We have been here nearly 10 years and we do need to see progress in the next year or two in order for people to be willing to see this through and believe that we can achieve the outcome for which we are all working.
"I think, at last, we do have our strategy and the resources - military and civilian - properly aligned and that's been true with the surge of troops but also the civilian effort that's come in this year."
Prime Minister David Cameron has said he wants to withdraw British combat troops from Afghanistan by 2015, and Mr Sedwill said of the five-year timeline: "We can achieve a great deal in that time."
He went on: "It's impossible to say exactly how long we will need, but we do need to take this at the right pace and we will need to be patient. But that doesn't mean we need to be here forever, and the kind of timelines that we have been hearing about, 2014, 2015, are realistic."
Talking to members of the insurgency, including the Taliban, would be an "uneven process", Mr Sedwill predicted as he said there were "channels of communication open".
"I wouldn't say at this stage we are seeing real negotiation," he said, adding that the insurgents have "really given up trying to compete for the hearts and minds and are simply now trying to intimidate the population".