WASHINGTON—U.S. President Joe Biden on Sunday called on Afghanistan’s Taliban terrorist group to release a U.S. civil engineer who was abducted two years ago and is believed to be the last American hostage held by the Taliban. Mark Frerichs, a 59-year-old U.S. Navy veteran from Lombard, Illinois, who worked in Afghanistan for a decade on development projects. He was kidnapped a month before the February 2020 U.S. troop pullout deal was signed and was transferred to the Haqqani network , a brutal Taliban faction accused of some of the deadliest attacks of the war. Monday marks his second year in captivity. “Threatening the safety of Americans or any innocent civilians is always unacceptable, and hostage-taking is an act of particular cruelty and cowardice,” Biden said in a statement. “The Taliban must immediately release Mark before it can expect any consideration of its aspirations for legitimacy. This is not negotiable.” Biden …