WASHINGTON — U.S. forces in Afghanistan on Thursday struck an Islamic State tunnel complex in eastern Afghanistan with "the mother of all bombs," the largest non-nuclear weapon ever used in combat by the U.S. military, Pentagon officials said. The bomb, known officially as a GBU-43B, or massive ordnance air blast weapon, unleashes 11 tons of explosives. When it was developed in the early 2000s, the Pentagon did a formal review of legal justification for its combat use.