South Korea on Friday termed North Korea a grave threat, a further sign of the deepening chill in relations between the two since Pyongyang’s nuclear test nearly three months ago. A defence white paper used some of the harshest language to describe its communist neighbour since the South tried to set aside decades of outright hostility towards the North with the diplomacy of what Seoul dubbed its “sunshine policy”. “North Korea’s conventional forces, its nuclear test, weapons of mass destruction and the forward deployment of its troops are a grave threat to our security,” the white paper said. Two years ago, the term it used was “direct military threat”.