The Islamic State group has lost its caliphate in Syria and Iraq, but in the forbidding mountains of northeastern Afghanistan the group is expanding its footprint, recruiting new fighters and plotting attacks on the United States and other Western countries, according to U.S. and Afghan security officials.

Nearly two decades after the U.S.-led invasion, the extremist group is seen as an even greater threat than the Taliban because of its increasingly sophisticated military capabilities and its strategy of targeting civilians, both in Afghanistan and abroad. Concerns run so deep that many have come to see the Taliban, which have also clashed with IS, as a potential partner in containing it.

Read more: AP