North Korean Mine South of Border Line Was Deliberately Placed, Investigation Finds

South Korea’s Joint Chiefs of Staff said Monday that a North Korean anti-personnel mine found south of the Military Demarcation Line had been deliberately placed there more than 12 months ago, citing the final findings of a United Nations Command investigation.

Army Lt. Gen. Kwon Dae-won, vice chairman of the Joint Chiefs of Staff, announced the result at a briefing in Seoul on the Sept. 21 mine explosions inside the Demilitarized Zone. Three South Korean military personnel were injured in the blasts.

The United Nations Command, which oversees the armistice that halted fighting in the 1950-53 Korean War, had previously said investigators discovered a North Korean anti-personnel mine on the southern side of the demarcation line. It concluded that the presence of the mine constituted a violation of the Armistice Agreement. The latest account added the assessment that the device had been intentionally installed and had remained there for more than a year.

The Joint Chiefs said South Korean forces removed the North Korean minefield south of the line at about 12:51 p.m. Monday. It also called on Pyongyang to stop border fortification work near the demarcation line.

Questions about North Korean activity on the southern side of the line had emerged before the September explosions. People Power Party lawmaker Yu Yong-weon raised allegations during a parliamentary interpellation session that North Korean troops had planted mines south of the boundary. The Defense Ministry later said it had first identified a change in the terrain during the second half of 2025.

Democratic Party lawmaker Kim Byung-joo also said in late September that the mines were likely installed more than a year earlier. He linked them to North Korea’s broader border fortification campaign, which began in April 2024.

The findings sharpen the focus on how North Korea’s construction and mine-laying operations have affected the heavily fortified border. The Military Demarcation Line runs through the Demilitarized Zone and separates the two Koreas, while the Armistice Agreement provides the framework governing military conduct in the area.

The investigation did not attribute the Sept. 21 explosions to a newly planted device. Its estimate instead places the installation well before the incident and indicates that the mine had remained on the southern side of the line for an extended period. South Korean authorities have not announced any casualties from Monday’s removal operation.