The U.S. has blamed the Haqqani network, a major ally of al Qaeda in Pakistan, for an attack at the U.S. Embassy in Kabul that killed 16 people Tuesday. Five Afghan police officers and 11 civilians, including six children, were killed in the blast, more than double the number of casualties originally reported. The Haqqani network has emerged as the U.S.’s most deadly foe in the Pakistan border region, with attacks that typically involve several fighters and elaborate planning. The Pakistani government has been slow to go after the group as relations with the U.S. have soured over drone attacks and the killing of Osama bin Laden.