North Korea has been carving out roads, burying land mines and erecting iron fencing along the inter-Korean military demarcation line, according to 読売新聞, in what the newspaper describes as an effort to turn the border zone into a fortified line. South Korea's military has begun clearing mines laid south of the boundary, and military activity on both sides has picked up, feeding concern about a possible clash.
The reporting is based partly on direct observation. From the northern shore of Ganghwa Island, roughly two kilometers from North Korean territory, a 読売新聞 correspondent using a telephoto lens saw uniformed North Korean soldiers begin road-construction work around 1 p.m. on October 20. White stakes stood at regular intervals along both sides of the route.
A South Korean government official told the newspaper on October 21 that the scene showed work on either a "tactical road" able to carry military vehicles or a "mobility path" for troops on foot. North Korea is said to be building roads east to west along the roughly 250-kilometer boundary so that materiel and personnel can be moved quickly. The work reportedly follows a sequence: blasting the grass, leveling the ground, then laying the road surface.
A woman in her fifties who grew up on Ganghwa Island said that from late September into early October she heard repeated explosions and saw white smoke rise on the opposite shore. She described the experience as frightening and unlike anything she had seen before.
Why it matters
The demarcation line has long been one of the world's most heavily guarded borders, and the current construction work changes its physical character. According to 読売新聞, North Korean leader Kim Jong-un designated South Korea as a hostile state in 2023, and from April 2024 the North is believed to have started building roads, planting mines and putting up fencing near the line. The newspaper reports that the aims include treating the boundary as a national border and preventing defections.
South Korea's military expects the fortification work to be finished by 2028, according to the report.
Rising incidents and a warning from Pyongyang
More activity near the line has brought more friction. South Korea's military says confirmed incursions across the demarcation line by North Korean troops numbered nine in 2024 and seventeen in 2025, and have already exceeded fifty this year, 読売新聞 reports. In September, South Korean service members were injured when they stepped on a mine laid by the North, and the two sides traded sharp accusations afterward.
On October 21, the Korean Central News Agency reported that Pak Jong-chon, an adviser to North Korea's Ministry of National Defence, inspected the fortification site and said the enemy's reckless moves must be answered with overwhelming military action, according to 読売新聞. Kim Yo-jong, director of the party's general affairs department and the leader's sister, accompanied him.
Two days earlier, Kim Yo-jong issued a statement saying the North was considering deploying additional tactical strike means near the demarcation line. She accused South Korea's military of repeatedly staging warning broadcasts and warning shots while claiming North Korean troops had crossed the boundary.
Yoo Yong-won, a lawmaker with the opposition People Power Party who sits on the National Assembly's national defense committee and follows North Korean affairs, told 読売新聞 on October 21 that if North Korean forces return fire during South Korean warning shots, an accidental armed clash could follow. He said the situation around the demarcation line is bound to raise tensions.
What to watch is whether the road-building and mine-laying continue at the current pace through the end of the year, and whether either side's warning measures near the line escalate into an exchange of fire.
