From the Korea Times: Andrei Lankov 9/3/2006 In days gone by, underground mining was an important military activity, an essential part of any protracted siege campaign. Military miners, known as sappers, were discreetly digging tunnels under the walls and towers of the enemy castle, in the hope of collapsing them or, in later eras, stuffing … Continue reading DPRK tunnnels under the DMZ