“DAMMIT, DAMN, damn, damn!” A young Afghan girl lay dead and Mike Waltz seethed in frustration. An Afghan police unit working with Green Berets under Mr Waltz’s command had killed the child with indiscriminate gunfire unleashed in response to a Taliban attack. The shooting was justifiable but the police had ignored their training, Mr Waltz writes in “Warrior Diplomat”, a memoir published a decade ago about his combat service and tours as a Washington policymaker. The book doubles as a primer on the causes of America’s military failure in Afghanistan and an intellectual autobiography of the man Donald Trump has selected to be his national security adviser.