NEW YORK—A former Taliban commander previously accused of kidnapping an American journalist pleaded not guilty on Friday to murdering three U.S. soldiers in Afghanistan in 2008, telling a federal judge that the “accusations are incorrect.” Haji Najibullah, 45, appeared in federal court in Manhattan to enter the plea after prosecutors last week unveiled new charges against the accused former Taliban commander in Afghanistan’s Wardak Province, adjacent to Kabul. The indictment alleged that Taliban fighters under Najibullah’s command attacked a U.S. military convoy, killing U.S. Army Sergeants First Class Matthew Hilton and Joseph McKay, Sergeant Mark Palmateer, and their unnamed Afghan interpreter. Najibullah—wearing a beige button-down short-sleeve shirt, a white skullcap, and a white mask over his beard—entered the courtroom handcuffed and with a chain around his waist before pleading not guilty to terrorism-related offenses. If convicted, he could face life in prison. Najibullah is charged with 13 counts, including providing …