North Korean crosses heavily fortified border to South Korea   

An unidentified North Korean man crossed the heavily fortified land border separating the two Koreas and is in South Korean custody, the South's military said Friday.

The South's Joint Chiefs of Staff said the military identified and tracked the individual near the central-west section of the military demarcation line Thursday night and conducted a “guiding operation” to take the person into custody.

It said authorities plan to investigate the border crossing and did not immediately say whether they view the incident as a defection attempt. The Joint Chiefs said it wasn't immediately detecting any signs of unusual military activity by the North.

Border tensions have flared in recent months as the two Koreas traded Cold War-style psychological warfare, with North Korea sending thousands of trash-filled balloons toward the South and South Korea blasting anti-Pyongyang propaganda through loudspeakers.

Since taking office last month, South Korea's new liberal President Lee Jae Myung has made efforts to rebuild trust with North Korea, halting the frontline loudspeaker broadcasts and moving to ban activists from flying balloons carrying propaganda leaflets across the border.

In April, South Korean troops fired warning shots to repel about 10 North Korean soldiers who briefly crossed the military demarcation line. The South's military said the soldiers returned to North Korean territory without incident and that the North didn't return fire.

In June last year, North Korean troops crossed the border three times, prompting South Korea to fire warning shots. Experts suggested these crossings may have been accidental, occurring as North Korean troops added anti-tank barriers, planted mines and carried out other work to bolster border defences amid escalating tensions between the Koreas.

Diplomacy between the war-divided Koreas has derailed since the collapse of denuclearisation talks between Washington and Pyongyang in 2019, which prompted North Korean leader Kim Jong Un to accelerate the expansion of his military nuclear programme and threaten nuclear conflict toward Washington and Seoul.

South Korea's previous conservative government responded by strengthening its combined military exercises with the United States and Japan, which the North condemned as invasion rehearsals.