The South Korean military fired warning shots last week after a group of soldiers from North Korea crossed the demarcation line between the rival countries, Yonhap news agency reported on Sunday.

Seoul said the North Korean soldiers crossed the border in the eastern part of the demilitarised zone in what was the first such violation this year. The soldiers were patrolling the area when they crossed over into South Korea, the news agency reported, citing an unnamed government source.

After the South Korean military fired the warning shots, the intruding troops returned to their side and there was no other unusual activity after that.

“North Korea’s military recently violated the military demarcation line on the eastern front and the South Korean military fired warning shots in accordance with the operational procedures," the joint chiefs of staff of South Korea said in a statement.

"The South Korean military maintains a firm military preparedness while closely monitoring the North Korean military's trends.”

As per existing norms, South Korean military personnel must air warning broadcasts if they spot North Korean troops approaching the demarcation line and fire warning shots if they cross the boundary.

The two Koreas are technically still at war as the 1950-53 Korean War ended in a ceasefire rather than a peace treaty.

North Korean troops violated the demarcation line 17 times last year, according to the South Korean military.

There was a spike in incidents of North Korean soldiers crossing the demarcation line after Pyongyang declared South Korea a “hostile state” in 2023.

Observers, however, attributed most of the incidents to dense foliage in the area preventing them from spotting signs marking the demarcation line.

The crossings have tapered off since Pyongyang completed the primary phase of land-clearing along the border.

At the same time, Pyongyang has fortified its side of the demarcation zone, which has long been one of the most heavily militarised places in the world.

It has deployed more troops near the border to clear trees, construct anti-tank barriers, lay mines, and build tactical roads.