North Korea vows 'merciless' action to protect border

North Korea vowed Friday to take merciless military action to protect its Yellow Sea border with South Korea and warned that Seoul would pay dearly for a naval clash this week. Our side reminds your side again that there exists only a demarcation line in the West Sea (Yellow Sea) set by our side, and from this moment on we will take merciless military measures to protect it, its military said in a message to the South's forces. The North refuses to recognise the sea borderline set by the United Nations after the 1950-53 war and demands that it be drawn further to the south.The new warning came just five days before US President Barack Obama visits Seoul for talks expected to focus on North Korea's nuclear programme.