The South Korean military fired warning shots last week after a group of North Korean soldiers crossed the inter-Korean land boundary, prompting them to return to their side, a source said Sunday. Multiple North Korean soldiers crossed the Military Demarcation Line (MDL) in the eastern front-line area sometime last week, prompting the warning shots under the military's operational procedures, according to the government source. It marked the South Korean military's first warning shots this year in response to North Korean troops crossing the boundary. No prior MDL violations by the North Korean military had been reported this year. The soldiers were said to have been likely patrolling the area when they crossed the MDL, which bisects the Demilitarized Zone separating the two Koreas — a legacy of the 1950-53 Korean War. The North Korean troops returned to their side after the warning shots, and no other unusual activity was reported. Under rules of engagement, the South Korean military airs warning broadcasts if North Korean troops approach the MDL, followed by firing warning shots if th