WASHINGTON, July 2 (Reuters) - U.S. President Joe Biden on Friday said the withdrawal of American troops from Afghanistan is "on track" but it will not be completed within the next few days. Speaking to reporters at the White House, Biden said that some U.S. forces will still be in Afghanistan in September as part of a "rational drawdown with our allies." Biden in April set the deadine for completion of the pullout from America"s longest conflict as the anniversary of the Sept. 11, 2001, attacks by al Qaeda on the United States that prompted the U.S.-led invasion of Afghanistan. Biden"s comments came hours after the last American troops left Bagram Air Field, which served as the main U.S. military base in the country, leaving behind a piece of the World Trade Center buried there two decades ago. read more The departure of U.S.-led forces, fierce fighting that has seen Taliban advances around the country and stalled peace talks have fueled fears that Afghanistan is on a path to all-out civil war that could restore the insurgents to power. Biden said he is concerned that President Ashraf Ghani"s beleaguered government deal with "internal issues" in order to "generate the kind of support they need nationwide."