A man looks at a photo of the launch of a missile hanging on the wall of a factory workers' dormitory in Pyongyang. (AP file photo) SEOUL--North Korea has been enslaving political prisoners, including children, in coal production to boost exports and earn foreign currency as part of a system directly linked to its nuclear and missile programs, a South Korea-based human rights group said on Thursday. The Seoul-based Citizens’ Alliance for North Korean Human Rights (NKHR) released a study analyzing an intricate connection between North Korea’s exploitation of its citizens, the production of goods for export, and its weapons programs.