North Korean soldiers cross border into South Korea twice: Seoul military

Dozens of North Korean soldiers had briefly crossed the heavily fortified border with the South and retreated after warning shots were fired.

It is the second such incident involving North Korean troops in two weeks, according to Seoul's Joint Chiefs of Staff on Tuesday.

Seoul's military said they believed the latest crossing — like a previous one on June 9 — was accidental.

The two Koreas remain technically at war as the 1950-1953 conflict ended in an armistice, not a peace treaty, with the demilitarised zone and line of control dividing the peninsula into one of the most heavily mined places in the world.

Seoul's military also said Tuesday that several North Korean soldiers had been injured when a landmine exploded near the border without revealing the date.

The North Koreans were working on creating "barren land" and laying mines along the border, an official from the JCS said, but ended up "suffering multiple casualties from repeated landmine explosion incidents during their work".

Even so, the North's military "appear to be recklessly pressing ahead with the operations," the official said.

Increased DMZ activity

This year, North Korea has been working to remove streetlights from roads and dig up railway tracks that connected the two countries when ties were better, they added.

Since April, North Korea has deployed troops along the front line "to create barren land", the official said, adding the North was also laying more landmines, reinforcing tactical roads and adding what appeared to be anti-tank barriers.

"North Korea's activities seem to be a measure to strengthen internal control, such as blocking North Korean troops and North Koreans from defecting to the South," the JCS official said.

Relations between the two Koreas are at one of their lowest points in years.

In recent weeks, North Korea has sent more than a thousand balloons laden with trash, including cigarette butts and toilet paper, southward — a response, it says, to balloons carrying anti-Pyongyang propaganda sent north by activists.

"The recent increase in the entry of North Korean military into the DMZ (Demilitarised Zone) is due to the need for mine clearance and surveying for the installation of barriers," Ahn Chan-il said, a defector-turned-researcher who runs the World Institute for North Korea Studies.

"Engineering and observation units have increased their presence in the area. It is believed that the disorderly actions of those who are unfamiliar with the minefields have led to these mine-related accidents."