Chun Chung-nam had tried to kill himself by biting off his tongue. The first time I met him, faint traces of his failed attempt were still evident on his face—a healing cut on his left lip where a South Korean soldier had forced his jaw open. Chun, twenty-seven, was the leader of a two-man North Korean commando squad intercepted while trying to contact one of the communist North’s resident agents near Tadaepo, a seaside resort west of Pusan (also spelled Busan), South Korea’s largest port. Minutes after he and his comrade-subordinate, Lee Sang-gyu, twenty-three, landed from a semi-submersible submarine, South…