South Korea is preparing a response to force North Korea to apologise for a mine blast in the Demilitarized Zone. The blast on September 21 wounded three South Korean soldiers. Two of them were seriously injured. Defence ministry spokesperson Chung Bin-na made the statement on October 6. A joint investigation with the United Nations Command found North Korean mines caused the blast. GPS measurements placed the blast sites about 10 meters south of the Military Demarcation Line. Investigators concluded the mines were deliberately buried. The finding means the mines violated the Korean Armistice Agreement. The Military Demarcation Line has divided the Korean Peninsula since 1953. It stretches more than 200 km with 1,900 markers. South Korea cleared the minefield on October 5 in coordination with the UN Command. The military destroyed the mines in a controlled explosion. North Korea rejected the accusation as groundless on October 3. Its state agency KCNA dismissed the demand for an apology. Kim Yo Jong said Pyongyang did not deliberately plant mines in the border zone. Seoul also wants talks on the exact line that separates the two Koreas. Officials admit the two sides use different references to locate the line.