Ag AFPKABUL/ISLAMABAD: The United States formally began withdrawing its last troops from Afghanistan Saturday, bringing its longest war nearer to an end but also heralding an uncertain future for a country in the tightening grip of an emboldened Taliban. US officials on the ground say the withdrawal is already a work in progress -- and May 1 is just a continuation -- but Washington has made an issue of the date because it is a deadline agreed with the Taliban in 2020 to complete the pullout....