Five North Korean soldiers crossed Saturday the inter-Korean borderline, or the Demilitarized Zone, then retreated northward after South Korean soldiers fired warning shots.

The Joint Chiefs of Staff in Seoul said the five soldiers, including one who was armed, went 30 meters over the border to the South at 11:56 a.m. despite five warnings broadcast by South Korean soldiers.

The North Koreans returned to their post around 1:15 p.m. after South Korean soldiers fired three warning shots.

The Joint Chiefs of Staff said the North Korean soldiers made the intrusion with a clear purpose, but that it does not believe the North wanted to escalate military tension before its planned nuclear test.