Demilitarized no more? North Korea's DMZ fortifications creep south as Seoul, UNC differ over signficance.

North Korea has erected barbed-wire fences to within 80 meters (262 feet) of the line dividing the two Koreas and cleared ground for land mines just 5 to 10 meters from it, the closest such fortification work has been confirmed near the line.

However, the Ministry of National Defense and the United Nations Command (UNC) disagree on whether it violates the Armistice Agreement. 

The work is moving faster than South Korean officials expected. What military planners once thought would take more than four years could now be completed in two to three years, as Pyongyang pours unprecedented manpower into sealing the border. In doing so, the North is nudging the boundary itself southward and turning the demilitarized zone (DMZ), the buffer meant to keep the two armies apart, into an armed frontier.

Multiple military sources and the office of Rep. Kang Dae-sik of the People Power Party, who sits on the National Assembly's National Defense Committee, said Sunday that North Korean troops have run fencing to within 100 meters of the military demarcation line (MDL), the de facto border, at points along the western, central and eastern fronts. It is the first time the barriers have been confirmed this close to the line.

The buildup traces back to North Korean leader Kim Jong-un's declaration that the two Koreas are hostile, separate states. In October 2024, the North said it would permanently seal its "southern border" and begin fortifying it, and it has been laying fencing and mines since. The barriers now sit almost on top of the MDL.

Ahead of the fences, the North is planting minefields to keep its own soldiers and residents from fleeing south. The preliminary step, stripping the ground bare, has already been done at points just 5 to 10 meters north of the line, and in some stretches, the work may have crossed to the southern side, by Seoul's reckoning. The Joint Chiefs of Staff (JCS) believes fencing now runs along about a third of the MDL, with room to push closer still. As the line advances, the North's guard posts can move south with them.

Behind the fences, the North is laying tactical roads that would allow its border troops to drive almost to the MDL for patrol. A wider North Korean presence inside the DMZ would force South Korean units to work harder to watch the line.

Former military officials worry the buildup effectively pushes the MDL south. Once the North anchors fencing to its version of the line, undoing the work becomes difficult, and the North's version of the boundary could harden into the real one. Since the 1953 armistice, the two Koreas and the United Nations Command have marked the line differently. Three competing versions now coexist.

"The whole point of the DMZ is to be a buffer that separates the two Koreas' militaries, but if guard positions are pushed forward behind the barbed wire and tactical roads, the chance of an accidental clash grows," said Moon Seong-mook, a retired Army brigadier general who heads the Unification Strategy Center at the Korea Research Institute for National Strategy.

The JCS also concluded that the North effectively finished clearing the ground along the front line late last year, completing the groundwork to turn the MDL into a sealed border. As of this month, along the roughly 250 kilometers (155 miles) of the MDL, the North has built up to 70 kilometers of tactical roads and about 90 kilometers of fencing.

Work that paused for the winter resumed in March and has proceeded briskly since. The North mobilized about 5,000 people in the first half of this year, up from around 1,000 in the same period a year earlier. At that rate, the South Korean military expects the North to finish sealing the border within two to three years. When the work began in the first half of 2024, Seoul had estimated it would take more than four years. The JCS now says the timeline has shrunk by more than a year.

The effort may itself signal that the North no longer intends to honor the demilitarized terms of the armistice. The DMZ extends 2 kilometers on either side of the MDL, so work just 5 to 10 meters from the line suggests the North means to militarize its entire half of the zone.

"North Korea's installation of barriers near the MDL constitutes a clear violation of the Armistice Agreement," the Defense Ministry said. 

This marks the first time the government has explicitly characterized the North's frontline construction activities as an Armistice violation. The ministry added that the Armistice Agreement stipulates that the DMZ was established as a buffer area to prevent incidents that could lead to a resumption of hostilities.

However, the UNC stopped short of characterizing the activity as an Armistice violation.

"Activities within the DMZ must be understood in their full context," the UNC told the JoongAng Ilbo. "Construction, fortification, defensive measures or the presence of personnel do not automatically constitute Armistice Agreement violations. Each matter is assessed based on the specific facts, circumstances, location, purpose and applicable provisions of the Armistice Agreement and subsequent agreements."

The UNC added, "When appropriate, UNC addresses Armistice-related concerns through established mechanisms and remains committed to reducing risk, preventing miscalculation and preserving peace and stability on the Korean Peninsula."

With the Defense Ministry and UNC holding different views, the Defense Ministry said it will "continue to communicate closely with the UNC and coordinate our response."

The differing assessments come as North Korea continues efforts to turn the MDL into what it describes as a permanent border between the two Koreas.

Kim, who has steadily cut links with the South, summoned division and brigade commanders from across the military last month and pressed them to build up forces along the line. He stressed the ruling Workers' Party's "policy of territorial defense on strengthening the first-line units in the southern border and turning the border line into an impregnable fortress."

"Fortification, at its core, means the intent to arm," said Yang Uk, a senior research fellow at the Asan Institute for Policy Studies. "It can be read as the North declining to follow the existing DMZ standards on matters like bringing in weapons, to build a defensive line and secure the ground north of the MDL."

"Our military is closely monitoring the North Korean military's work around the MDL and is managing the situation in a stable manner while maintaining a firm military readiness posture," the JCS said. "Our military maintains the capability and posture to respond overwhelmingly to any provocation by the North."

 BY LEE YU-JUNG [[email protected]]