More than a week after two land mines exploded in the Demilitarized Zone (DMZ), injuring three South Korean soldiers, investigators are getting a clearer picture of what caused the blasts, though questions remain over when and why the mines were planted. The United Nations Command said Wednesday that an active North Korean anti-personnel mine was found south of the Military Demarcation Line (MDL) during a joint investigation into the Sept. 21 DMZ explosions, determining that a violation of the 1953 Korean Armistice Agreement had occurred. South Korea's military believes the mines were buried rather than washed into the area but has yet to determine when they were planted or whether they were intended to target South Korean troops. What was found The intact mine recovered during the investigation was a North Korean resin anti-personnel mine, a box-shaped device similar to the North’s wooden-box mine but made of plastic. The JCS says North Korea has used this type since 1969. Forensic analysis of the injured soldiers’ helmets and body armor detected TNT and brown foreign material but no