North Korea on Tuesday warned of an "immediate and powerful counteraction" if South Korea intrudes even "a millimeter" into its territory, after Seoul signaled corresponding measures over a recent land mine blast at the inter-Korean border that it has blamed on Pyongyang. The North's foreign ministry issued the statement a day after the South's military concluded the mines planted by North Korea caused the Sept. 21 blast on the southern side of the Demilitarized Zone (DMZ) that left two South Korean soldiers critically injured. The South's military also conducted a mine-clearing operation at the blast site on the same day, in coordination with the U.N. Command (UNC), which oversees the border area. "We do not care about them trying to remove the mines irrelevant to us, and we have no reason to pay heed to such farce of the ROK," the ministry said, calling South Korea by its official name, the Republic of Korea. "However, if a jackboot or a spark of fire from the ROK goes even a millimeter beyond the border to violate our territory, the border guard forces of the DPRK will take an immedia