A group of armed North Korean soldiers crossed the military border into the South and returned to the North instantly after receiving warning shots, a South Korean Army source said Sunday.



"The military sent a warning message and fired warning shots after some 10 North Korean soldiers crossed the Military Demarcation Line near Cheorwon, Gangwon Province, at about 8 to 9 a.m. on Saturday," the source said. "The North Korean soldiers were armed and retreated after the warning shots. They didn't fire back."



This marked the first time this year that the South Korean military has fired warning shots at North Korean soldiers for intruding.



In October, soldiers of the two Koreas exchanged fire across the heavily armed border as North Koreans responded to the South's warning shots when they approached the MDL in Paju, Gyeonggi Province. There were no reports of casualties or property damage on both sides.



It was not immediately known what prompted the North Korean soldiers to try to cross the border in Cheorwon, a city located 88 kilometers north of Seoul.



The soldiers are believed to be working to check the state of a sign for the MDL, according to the source.



South Korea has been on alert against the North Korean Army's recently increased reconnaissance and other activities in border areas.



Last month, Adm. Choi Yun-hee, chairman of South Korea's Joint Chiefs of Staff, called for a watertight readiness against possible provocations by North Korea during his visit to a front-line Army unit.



He said the North is intentionally heightening tensions to break through unfavorable internal and external conditions.



"We're trying to analyze the motive behind the North Korean Army's increased activities near the MDL this summer season," the source said. "The military is fully ready for any emergency, tightening vigilance against any attack." (Yonhap)