North Korea’s laying of landmines along its heavily fortified border with the South has laid bare how misaligned the two nations have become over their de facto land boundary, after three South Korean soldiers were wounded in an explosion last month. Seoul blames Pyongyang for the blast near the military demarcation line (MDL) on September 21, in which one soldier lost a foot. On Tuesday, its Foreign Ministry said in a statement it was preparing a response to force an apology for the blast,...