South Korea fires warning shots after new border incursion

SEOUL, South Korea — Seoul's military said Friday it had fired warning shots after North Korean soldiers briefly crossed the heavily fortified border in the third such incursion this month.

The nuclear-armed North has been reinforcing the border in recent months, adding tactical roads and laying more landmines, which has led to "casualties" among its troops due to accidental explosions, South Korea has said.

On Thursday morning, "several North Korean soldiers who were working inside the DMZ on the central front line crossed the Military Demarcation Line," Seoul's Joint Chiefs of Staff said.

"After our military's warning broadcasts and warning shots, the North Korean soldiers retreated back northward," they added.

Similar incidents took place on June 9 and Tuesday this week, with Seoul's military saying both incursions appeared to be accidental.

Relations between the two Koreas are at one of their lowest points in years, with Kim Jong Un hosting Russian leader Vladimir Putin this week, and signing a mutual defence agreement that has raised hackles in Seoul.

In response, the South -- a major weapons exporter -- has said it will "reconsider" a longstanding policy that has prevented it from supplying arms directly to Ukraine.

"While attention is focused on Putin's pariah partnerships, the Kim regime is recklessly endangering soldiers with rushed construction work at the inter-Korean border," said Leif-Eric Easley, a professor at Ewha University in Seoul.

The work is likely aimed "as much at keeping their countrymen in as it is at keeping the South Koreans out," he said, but warned that "a lack of inter-Korean communication channels and confidence-building mechanisms increases the danger of escalation in border areas."

The two Koreas have also been locked in a tit-for-tat "balloon war", with an activist in the South confirming Friday that he had floated more balloons carrying propaganda north.

The move is likely to trigger a response from Pyongyang, which has already sent more than a thousand of its own balloons carrying trash southward.

Kim's powerful sister Kim Yo Jong, a top regime spokesperson, said Friday that "dirty tissues and items" had been detected near the