evidence: Bloodshed and violent confrontations have occasionally occurred at the Koreas’ heavily fortified border, called the Demilitarized Zone. While Sunday’s incident happened amid simmering tensions between the two Koreas, observers say it won’t likely develop into another source of animosity as South Korea believes the North Koreans didn’t deliberately commit the border intrusion and North Korea also didn’t return fire. At 12:30 p.m. on Sunday, some North Korean soldiers who were engaged in unspecified work on the northern side of the border crossed the military demarcation line that bisects the two countries, South Korea’s Joint Chiefs of Staff said. [...] Lee gave no further details. But South Korean media reports said that about 20-30 North Korean soldiers had entered South Korean territory about 50 meters (165 feet) after they likely lost their way. The reports said most of the North Korean soldiers were carrying pickaxes and other construction tools.