South Korea's military said it is highly likely that a North Korean military mine caused the explosion on the 21st in the Demilitarized Zone along the western front, and that it will take "corresponding measures" if the device is confirmed to be a mine planted by the North.
Maj. Gen. Yang Jin-hyuk, director of operations at the Joint Chiefs of Staff, said at a briefing on the 28th that the explosion is presumed not to have been caused by a South Korean mine, citing the shape of the crater and accounts of the flames identified at the site, along with the extent of the injuries to the wounded soldiers. Yang added that initial forensic findings from the National Forensic Service make it certain the blast was not caused by a South Korean mine, given that brown foreign matter was detected and no steel fragments were found.
The military believes the device was likely a plastic-cased anti-personnel mine similar to the wooden-box mines used by the North Korean military. The North Korean military's plastic anti-personnel mine, part of the PMN series, has an outer casing made of plastic resin.
The blast occurred about 10 meters south of the Military Demarcation Line. The site was confirmed to be about 10 meters from an area where terrain changes suggested North Korean forces had recently planted mines. The military said there is no record of South Korean forces having laid mines in the area where the explosion occurred.
The wooden-box mines used by the North Korean military are known to contain about 220 grams of TNT explosive. The military presumes the blast came from the explosive power of a North Korean mine, noting that the site is not an area where South Korean forces installed M14 and M16 anti-personnel mines and pointing to the extent of the injuries.
The military says that if it secures an unexploded mine through further investigation, it will be able to determine the type and origin of the device precisely by analyzing not only its exterior but also its material, explosive composition and manufacturing method.
Even if the device is confirmed to be a North Korean mine, further questions remain: whether it drifted from its original location along nearby streams, or whether North Korean troops crossed the MDL and planted it deliberately. If the latter is confirmed, whether it constitutes a violation of the armistice agreement could become a point of contention.
Initial forensic analysis of the wounded soldiers' gear, which the military requested from the National Forensic Service, detected TNT residue and brown foreign matter. The service delivered the initial findings to the military at about 4 p.m. on the 28th.
Kwon Dae-won, vice chairman of the Joint Chiefs of Staff, said that if the final investigation determines that the casualties were caused by a mine planted by North Korean forces, it would mean that South Korean soldiers conducting routine DMZ operations south of the MDL were wounded by a North Korean mine.
"All responsibility for this lies with North Korea," he said. "Our military will carry out appropriate and corresponding measures."
South Korea's military and the United Nations Command conducted a second day of on-site investigation on the 28th, after beginning on the 27th. The final findings will be announced after an assessment with the U.N. Command.
As the joint investigation team began its full on-site inquiry, political conflict has intensified not only over the cause of the accident but also over the delay in the investigation. The People Power Party has taken issue with why the on-site investigation was delayed and formally moved to pursue a National Assembly hearing and a parliamentary investigation. The Democratic Party of Korea countered that political attacks should be restrained while the investigation into the cause is still under way.
The People Power Party also alleged that the military deliberately concealed its initial assessment of the origin of the explosive, which it suspected was a North Korean mine. Rep. Na Kyung-won of the People Power Party said at a news conference on the 28th that the phrase "presumed to be a North Korean wooden-box mine" had clearly been included in the military's first report but was deleted, and said she would introduce a resolution calling for the facts to be established and those responsible to be held accountable. She also called for the formation of a fact-finding team including experts recommended by both parties, and for an emergency joint hearing of the Foreign Affairs and Unification, Intelligence and National Defense committees.
Na argued in particular that the government had been aware of warning signs in advance but failed to take appropriate action, citing a fact sheet released by the U.N. Command on June 23. According to Na, the fact sheet stated that the U.N. Command was seriously aware of suspected North Korean crossings of the MDL and was investigating, in cooperation with South Korean operational commands, whether North Korea had crossed the line and laid mines. The U.N. Command is said to have subsequently conveyed to the South Korean government its view that an investigation was needed.
The National Assembly's National Defense Committee will hold a plenary session on the 29th to question officials on issues related to the accident. Rep. Lim Jong-deuk of the People Power Party, the opposition liaison on the committee, said he would thoroughly verify when the report on the unexploded mine was made and how the military assessed the possibility of North Korean troops approaching the area and of a North Korean mine.
