Military effectively concludes that North Korean mine caused series of blasts in DMZ

The military has effectively concluded that a recent series of blasts in the western section of the demilitarized zone (DMZ) was caused by a North Korean plastic antipersonnel mine.

The two explosions on Sept. 21 marked the first time in 11 years that South Korean troops suffered serious injuries from a North Korean mine, following the wooden box mine incident in 2015. The South Korean government, however, did not issue a separate warning to or criticism of North Korea, as the findings announced on Monday were still preliminary.

Lt. Gen. Kwon Dae-won, the vice chairman of the Joint Chiefs of Staff and head of the joint investigation task force into the matter, said that the military had determined that a North Korean mine was “highly likely” the cause.

Kwon cited several factors.

“There was no record of South Korea laying mines in the area, while traces of North Korean mine-laying activity nearby were discovered in September 2025,” he said.

He added that, in a preliminary analysis, the National Forensic Service detected traces of trinitrotoluene, or TNT, on the injured soldier’s body armor. But given the absence of metal fragments, the nature of the series of blasts, including the crater and explosion flames, and the extent of the damage, the military believes that the mine was different from the M16 antipersonnel one used by South Korean forces.

Statements from troops who took part in the operation also support the theory that a North Korean mine caused the explosions.

However, the military has yet to secure what it considers a “smoking gun” to prove that North Korea laid the mine.

After the explosions, the troops withdrew on their knees, with those at the front checking for mines by probing the ground at intervals of about 5 centimeters (2 inches), according to statements from those who took part in the operation.

Soldiers said that they saw “a rectangular mine with a plastic exterior” about 1 meter (3.3 feet) from the site of the blasts.

Military intelligence authorities believe that the mine described by the soldiers resembles a resin antipersonnel mine that North Korea has manufactured since 1969. That makes it less likely that the mine dated back to the 1950-53 Korean War.

The military plans to look for and recover this mine during an additional on-site investigation.

The blast site was also only about 10 meters from a minefield created by North Korean troops.

Previous satellite imagery showed that North Korean troops had been laying mines across the military demarcation line (MDL) in the area since August last year. Military officials have said that soil and grass have almost certainly already covered these mines, as grass can grow over mines within a year, even in an area without perennial vegetation.

That raises the possibility that North Korean troops planted the mines recently as part of fortification work.

The Sept. 21 incident occurred at around 10:51 a.m., when 18 soldiers from a reconnaissance battalion under the Army’s 25th Infantry Division, 1st Corps, were clearing a new patrol route.

The troops had been preparing for a joint on-site inspection with the United Nations Command (UNC) — related to North Korea’s fortification work along the MDL — by opening a new patrol route near the former Suuksi (translated) ferry site along the Imjin River.

The two explosions severed the ankle of the reconnaissance battalion commander and caused severe lacerations to the leg of a noncommissioned engineering officer. Both were taken to the Armed Forces Capital Hospital in Gyeonggi.

Questions remain over why the troops approached within about 10 meters of the MDL.

The UNC had reportedly not agreed to the route in advance. The South Korean government and the UNC have recently differed over operational authority inside the DMZ, causing some to question whether the South Korean military began clearing the route without sufficient prior coordination with the command.

“The accident site is an area where communications are poor, so GPS errors may have caused the troops to approach the MDL,” a South Korean military official said.

Valleys and ridgelines also reportedly make the place a blind spot.

Seven North Korean guard posts and four South Korean guard posts are positioned in the area, with the blast site lying about 740 to 870 meters northwest of a South Korean guard post. 

Military authorities formed a joint investigation task force with the UNC Military Armistice Commission on Thursday and conducted an on-site investigation on Sunday and Monday.

The South Korean government is expected to consider a stronger response if the final investigation concludes that North Korean troops had laid the mine.

“If the final investigation determines that our soldiers were injured by a mine laid by North Korean troops while lawfully carrying out DMZ operations south of the MDL, then our soldiers were injured by a North Korean mine,” Kwon said. “All responsibility lies with North Korea. Our military will take appropriate and corresponding measures.”

After the 2015 wooden box mine incident, the government resumed loudspeaker broadcasts featuring anti-Pyongyang messages toward North Korea on the same day that it announced the investigation results.

By contrast, the Lee Jae Myung administration suspended loudspeaker broadcasts toward North Korea in June last year and removed fixed loudspeakers from frontline areas in August.

Some within the military have discussed expanding operations to detect and remove North Korean mines near the MDL as a possible corresponding measure.

“If it’s true that North Korea planted mines near the MDL and endangered the lives of our soldiers, that can never be tolerated,” Rep. Park Sung-joon, a senior spokesperson of the ruling Democratic Party, stated in a written briefing after the military announcement. “North Korea must immediately cooperate in fully uncovering the facts of this incident.”

BY LEE YU-JUNG, SHIM SEOK-YONG [[email protected]]