The blasts that wounded three South Korean soldiers last week were apparently caused by North Korean mines, Seoul said Tuesday, accusing Pyongyang of an armistice violation and warning of "corresponding measures".
One soldier lost a foot due to the explosions in the Demilitarized Zone (DMZ), the heavily mined buffer zone that has divided the two Koreas since their 1953 armistice.
The northern and southern boundaries of the zone are among the world's most heavily fortified frontiers and landmine incidents have previously heightened tensions between the two Koreas, which remain technically at war.
South Korean Defense Minister Kang Shin-chul spoke before a parliamentary hearing a day after his ministry said North Korean mines were "highly suspected" of causing the two explosions last week.
"This is a clear violation of the armistice agreement, and since North Korea bears responsibility, we will take corresponding measures," AFP quoted him as saying.
The military "has a range of necessary measures at our disposal, and we will implement them in stages", he added, without giving details.
The minister said that dense vegetation in the area had hampered the work of mine detectors, and that South Korean forces were in the DMZ to clear the area in advance of an operation with the UN Command.
That operation would assess terrain changes caused by North Korean forces south of the Military Demarcation Line, which marks the nations' effective border.
Hong Sung-pyo, senior researcher at the Seoul-based Korea Institute for Military Affairs, said it was reasonable to conclude that the mines were North Korean.
"In practical terms, the only forces operating in the DMZ area are the South Korean, US and North Korean militaries," he told AFP.
"Given the interoperability between South Korean and US forces, there would be little reason for the US military to have laid any mines there."
Yang Jin-hyeok of the Joint Chiefs of Staff told lawmakers that a site investigation on Tuesday discovered an unexploded North Korean plastic anti-personnel mine.
Seoul and Pyongyang remain technically at war since the Korean conflict ended in a truce, not a peace treaty.
Since 2024, after North Korean leader Kim Jong Un designated South Korea as his country's "principal enemy", Pyongyang's military has laid mines and built anti-tank barriers along the frontier as part of efforts to permanently seal it off.
During the operation, Pyongyang also blew up the northern parts of inter-Korean roads no longer in use.
Minister Kang said Tuesday that the North Korean mines linked to the September 21 incident were believed to have been laid as part of Pyongyang's border fortification work.
There was no mention of last week's blasts on North Korean state media.
In a 2015 incident, two South Korean soldiers were seriously wounded in a landmine blast on the southern side of the DMZ, with one losing both legs.
Seoul concluded that North Korean troops had crossed the Military Demarcation Line to plant the mines, an accusation Pyongyang denied.
The incident prompted South Korea to resume anti-Pyongyang loudspeaker broadcasts along the border.
But Yang Moo-jin, former president of the University of North Korean Studies in Seoul, said that there is "very little South Korea can realistically do" in retaliation for the latest blasts.
"Resuming loudspeaker broadcasts would do more harm than good, particularly because residents in border areas would bear much of the disruption," he told AFP.
"That effectively leaves Seoul with few options beyond demanding an apology from North Korea and seeking assurances that such an incident will not happen again" -- unless it is willing to risk heightened military tensions and further escalation, he added.
