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 and conducted a “guiding operation” before taking the person into custody Thursday night.

Tens of thousands of North Koreans have fled to South Korea since the peninsula was divided by war in the 1950s, but defections across the land border are relatively rare.