North Korea appears to construct walls near DMZ, satellite images reveal CBS NewsNorth Korea Has Lost ‘Many’ Troops to Mines in DMZ, South Says The New York TimesHow Did North Korean Soldiers Wander Across the World’s Most Heavily Guarded Border? Military.comWhy North Korean Soldiers Keep Wandering Across the DMZ TIMENorth Korea Satellite Images Show Troops Building Border ‘Wall’ Newsweek