North Korea is blasting and fortifying its coast opposite Ganghwa Island, South Korea's military says

South Korea's military said on Tuesday, 13 October 2026, that a run of explosions heard from the North Korean side of the border opposite Ganghwa Island is most likely linked to North Korean troops reinforcing their coastal security facilities.

Capt. Jang Do-young, spokesperson for the Joint Chiefs of Staff (JCS), told a regular press briefing in Seoul that explosions were being heard continuously along the North Korean coast north of the neutral waters of the Han River estuary, in front of Ganghwa. He said the JCS judged that the North Korean military was strengthening coastal guard facilities on its side and that South Korean forces were closely monitoring related movements.

Blasting reported near Kaesong

The briefing came a day after Japanese public broadcaster NHK reported on 12 October that North Korea had been seen carrying out blasting work near Kaesong, north of Ganghwa, which it took to be demolition and fortification of the border area.

A Ganghwa resident in his 60s told NHK that the blasting appeared to be moving gradually from east to west and that the bangs sounded enormous because the work was so close. He said nothing like it had happened in more than 60 years of living on the island.

Korea JoongAng Daily ran a Yonhap photograph taken from Ganghwa on 12 October showing North Korean soldiers building a tactical road and fences near the border in Kaepung County, North Hwanghae Province.

A frontline island

Ganghwa Island sits just northwest of Incheon along the Han River estuary and is one of the South Korean islands closest to the Military Demarcation Line that divides the two Koreas. Yonhap noted that it is also one of the places where North Korean land mines often wash ashore after heavy rain.

Aju Press said the latest work fits a wider North Korean effort to harden its side of the border that began in October 2024, when Pyongyang announced it would cut the roads and railways linking the two Koreas and build defensive structures along the frontier.

The South Korean military did not say how long the blasting had been going on, how far it extends along the coast or what kind of facilities were being built, and it gave no sign that it saw the work as an immediate threat to the island.

Moving the fortification work to the western coastline opposite Ganghwa would extend North Korea's barrier-building beyond the land border into the estuary, an area where both militaries watch each other at very close range and where South Korean marines and residents live within earshot.