“But the al Qaeda ideology has adapted and has decentralised,” he said after meeting NATO military leaders in Brussels.Depmsey warned that instability in the Middle East and North Africa had allowed the al Qaeda to take advantage of it with an “arc” running across the region starting from Pakistan.“Now you find these groups are spread across an arc that runs roughly from Pakistan across the Arabian Peninsula, across the Middle East and North Africa and all the way down into Nigeria with Boko Haram,” Dempsey said.“But we also have to realise something has changed close to home - the eastern flank and southern flank - and that requires us to refocus on the threats that are real,” Dempsey said.Separately, Dempsey said that the Taliban should take advantage of what may be a shrinking window of opportunity to seek a negotiated end to the conflict in Afghanistan."I don't give military advice to the Taliban, but if I were giving them advice, I'd say, 'Your negotiating position is not going to improve; it's going to erode',” he said.Dempsey spoke after meeting NATO military leaders in Brussels as the alliance plans for what is expected to be a continued Western training mission in Afghanistan after most NATO and allied forces depart late this year.If a continued troop presence and financial backing for Afghan forces can be secured, "it would seem to me that the Taliban would realise that their opportunity to reconcile or reintegrate is a wasting opportunity," Dempsey said in an interview with Reuters and the Pentagon's official news agency. "If they don't take advantage of it now, they will be in a weaker position later."The Taliban is intensifying its annual summer insurgent campaign as Afghanistan prepares for second-round voting in a presidential election that will pick the country's first new leader in more than a dozen years.Afghanistan's next president will face daunting challenges. Its security forces still lack in key areas such as intelligence and air power, and foreign assistance that has sustained the impoverished country is diminishing.Many Taliban leaders have been captured and killed, and the group has been pushed out of much of its southern heartland. But it remains potent in remote areas along the Afghan border with Pakistan and is still able to plan attacks from Pakistan's northwest tribal region.US and NATO officials have pointed to a relatively peaceful first round of elections this spring, and other recent events for which Afghan forces provided security, as proof that Afghanistan is getting close to being ready to stand on its own after Western combat forces depart in December.Turnout was higher than expected in that vote despite Taliban warnings that Afghans should not take part."They haven't been able to convince the people of Afghanistan that their future should be with the Taliban and not with an elected government," Dempsey said."One might argue that I'm maybe trying to be a little overly optimistic about it because we've invested 12 years of our lives in it, but it does seem to me to be a clear statement on the part of the Afghan people," he said.It remains to be seen what the departure of President Hamid Karzai will mean for on-again, off-again Western efforts to broker a peace deal between the Taliban and Afghan authorities.The Obama administration has at several points appeared close to launching confidence-building measures that would enable peace talks, only to see the initiatives founder. The Taliban's leadership has consistently rejected direct talks with Karzai's government.