Seoul to Force Pyongyang Apology Over Korea DMZ blast

South Korea is preparing a response to force North Korea to apologise for the Korea DMZ blast that left three South Korean soldiers wounded, two of them seriously, a defence ministry spokesperson said Tuesday. The soldiers were on routine operations inside the demilitarized zone when the September 21 explosion tore through their route. The announcement is Seoul's toughest stance yet over a blast its military says was caused by mines the North deliberately planted south of the Military Demarcation Line.

The ministry's announcement followed a final determination issued Monday by the South's Joint Chiefs of Staff, closing weeks of uncertainty around the Korea DMZ blast. After a joint investigation with the United Nations Command and scientific analysis, Seoul concluded that the troops were hit by a plastic antipersonnel landmine laid by North Korea south of the demarcation line, under what Pyongyang describes as border fortification work. According to Lt. Gen. Kwon Dae-won, vice chairman of the Joint Chiefs, the landmine was buried only a few centimetres underground and was likely placed about a year ago. South Korea's army started clearing the minefield on Monday afternoon and said it would keep going if the North does not remove the landmines itself, Reuters reported.

Investigators say the physical evidence pointed in one direction. Fragments recovered at the Korea DMZ blast site contained TNT and thermosetting resin consistent with North Korean munitions, and matched North Korean plastic mines previously pulled from the Imjin River, down to the brown casing with a lattice pattern on the cover. GPS measurements put both blast sites and the spot where an additional landmine was found just south of the demarcation line. The UN Command separately found that the mines were placed deliberately, calling the planting a violation of the Korean War armistice, according to the Korea JoongAng Daily.

The blast sits on top of a border buildup that has been gathering pace for a while. North Korea has been fortifying its side of the frontier since April 2024, sending up to seven thousand workers this year to lay landmines and fences, with some 50 incidents of troops crossing the line, according to the South's military briefing. The Koreas never signed a peace treaty, so the fighting of 1950 to 1953 ended in an armistice and the two sides remain technically at war. Against that backdrop, Seoul treats a minefield inside the buffer zone as a deliberate provocation.

A border neither side can agree on

Part of what made the Korea DMZ blast so dangerous is how hard the actual border is to pin down. The Military Demarcation Line stretches more than 200 km (124 miles) between the east and west coasts, marked by 1,900 posts, and was drawn up when the Korean War ended. With almost no access to the zone for decades, some stretches of the line have become difficult to identify, and Seoul and Pyongyang hold different views of exactly where it runs. Defence ministry spokesperson Chung Bin-na said that disagreement is one factor feeding tension in the area, and called on the North to come to the table to talk through the misalignment. Chung also said Pyongyang must remove the landmines it planted south of the line, Reuters reported.

Pyongyang says it was never there

North Korea's answer to the Korea DMZ blast was a flat denial. Kim Yo Jong, the influential sister of leader Kim Jong Un, called Seoul's accusation groundless and said Pyongyang had not deliberately planted mines in the border zone, dismissing the demand for an apology, according to state news agency KCNA. The statement went further than answering the Korea DMZ blast claims, accusing Seoul of staging a provocation. South Korea's military points the other way, saying the joint findings with the UN Command, the buried placement of the landmines, and the recovered fragments answer the question.

What Seoul's promised response will actually involve remains unclear. Chung did not specify what measures the defence ministry is preparing, and the ministry gave no timeline for the apology demand. For now the concrete action is the landmine-clearing operation already underway, which the army says will continue until the field south of the line is gone. The Korea DMZ blast is the latest sign that the world's most fortified border is getting harder, not easier, to manage.