Investigation findings and DMZ clearance

South Korea's military completed a joint investigation with the United States-led United Nations Command into a September 21 explosion along the inter-Korean frontier. The blast injured three South Korean soldiers, two of them seriously, as they cleared vegetation to construct a patrol route inside the Demilitarized Zone. Joint investigators confirmed that North Korean landmines buried south of the Military Demarcation Line caused the detonation. The conclusion relied on forensic analysis of chemical traces of TNT retrieved from uniforms and the discovery of another unexploded North Korean device at the site days later. On October 5, South Korean forces cleared the surrounding minefield and announced they would eliminate any remaining North Korean minefields placed south of the line if Pyongyang refused to remove them.

Lt. Gen. Kwon Dae-won, vice chairman of the Joint Chiefs of Staff, demanded formal accountability during a televised briefing.

“Our military strongly urges North Korea to offer a sincere apology to our injured soldiers and immediately remove the mines that it installed in violation of an armistice agreement.”

South Korean measures and Pyongyang's denial

South Korean Defence Minister Kang Shin-chul defended the military's clearance operation as a decisive countermeasure to cross-border actions. Addressing the response, Kang rejected domestic arguments that the armed forces acted too passively or defensively following the casualties. He affirmed that the operation represented the first demining mission undertaken by South Korean forces inside the Demilitarized Zone since the armistice.

“Our comrades were seriously wounded by mines planted by North Korea under the pretext of border fortification. Therefore our army took the necessary steps.”

Defence ministry spokesperson Chung Bin-na announced on October 6 that Seoul is preparing further steps to force North Korea to apologize for the blast. Pyongyang dismissed the findings through state media. North Korea rejected the accusations on October 2 as groundless, warning of retaliation if South Korea escalated tensions over the incident. Kim Yo Jong, the sister of North Korean leader Kim Jong Un, denied that northern units deliberately planted mines across the border zone.

Demarcation disputes and border fortification

The dispute connects to conflicting interpretations of the Military Demarcation Line, which bisects the Demilitarized Zone across more than 200 kilometres from coast to coast. Established at the end of the Korean War in 1953, the border was marked by 1,900 separate posts, many of which have become difficult to locate after decades of limited access and heavy overgrowth. Spokesperson Chung stated that differing views regarding the precise line contribute directly to military friction in the area. South Korea had previously proposed working-level talks to clarify the boundary alignment in November 2025.

202517

202650

2025

17 crossings

2026

50 crossings

Data from the article text

The Demilitarized Zone contains an estimated two million landmines, alongside expanding defensive works. North Korea has added fresh minefields, anti-tank barriers, and barbed wire fences along the northern side of the boundary after leader Kim Jong Un declared South Korea his country's principal enemy. South Korea's military reported that North Korean personnel violated the Military Demarcation Line 17 times in 2025 and 50 times in 2026 during these construction works, prompting South Korean guard units to fire warning shots.