In the remote mountains of Afghanistan an unusual mission is underway. Large numbers of US troops have dropped in by helicopter to a place that has never seen Americans before. US intelligence believes that the wild region of Nuristan and Kunar is harbouring militants linked to al-Qaeda and other groups. Operation Mountain Resolve is aimed at destroying them and their bases. The US military has found it hard to locate al-Qaeda. Now, it says, its troops have fought some gun battles up here but that their enemy has been running away. Full Story