SEOUL, April 8, 2025 (BSS/AFP) - South Korea's military said Tuesday its troops fired warning shots when around 10 North Korean soldiers briefly crossed the heavily fortified border that divides the peninsula.

The troops were spotted around 5 pm (0800 GMT) in the demilitarised zone between the two countries, parts of which are heavily mined and overgrown. 

"Our military conducted a warning broadcast and fired warning shots, and the North Korean soldiers moved north," Seoul's Joint Chiefs of Staff (JCS) said in a statement.

"Our military is closely monitoring the movements of the North Korean soldiers and taking necessary measures," it said.

Some of the soldiers who crossed the frontier were armed and wearing bulletproof vests.

North Korean troops made a series of small border incursions last year, which Seoul said at the time were likely accidental.

South Korea's military on Monday flagged unusual activity by North Korean soldiers.

It came days after a Seoul court removed president Yoon Suk Yeol from office, prompting snap polls to be called for June 3.

Relations between the two Koreas are at one of their lowest points in years and Pyongyang has previously conducted missile launches or other provocations around the time of key South Korean events.

Around 1,500 North Korean soldiers were seen conducting land-clearing operations and installing barbed wire in frontline areas, JCS spokesman Lee Sung-jun said Monday.

"The North Korean military is currently conducting training," he said.

"It is expected that soon there will be tactical training or evaluation inspections."

South Korea's top brass has said it is prepared for any action by the North in the wake of Yoon's removal from office.

The two countries are technically still at war as the 1950-1953 conflict ended in an armistice rather than a peace treaty. 

With relations souring, the North last year blew up roads and railways connecting it to the South and fortified areas of the border with more mines. 
The two sides have traded blame over balloons flown across each other's borders, as well as blaring broadcasts at one another.

Seoul has also been alarmed by warming ties between Pyongyang and Moscow, after the pair signed a mutual defence agreement last year.

The North has subsequently sent thousands of soldiers as well as weapons to help Russia fight Ukraine.