North Korean troops working in the Demilitarized Zone (DMZ) separating the two Koreas briefly crossed the border into the South on Thursday before returning to their side after the South fired warning shots, the Joint Chiefs of Staff (JCS) said. The North Korean soldiers crossed the Military Demarcation Line within the DMZ in the central section of the border at around 11 a.m. Thursday, the JCS said in a message to reporters on Friday. The South Korean military conducted warning broadcasts and fired warning shots, prompting the North Korean soldiers to return to their side of the border, it said. A JCS official said the incident appears to be accidental, adding the soldiers soon resumed their jobs and continued working into the night after returning to the North. It marked the third border violation by the North this month after similar incidents involving a group of 20 to 30 North Korean soldiers in other areas of the central section of the border on June 9 and June 18, respectively. The JCS earlier sai d both cases appeared to be unintentional. The border violations came as North Korea has been deploying large numbers of troops in front-line areas since April to conduct an array of activities, such as planting mines, erecting walls assumed to be anti-tank barriers and reinforcing roads. Source: Yonhap News Agency