North Korea enters 'state of war' with South

Russia and China have been urging calm after North Korea said it is entering a "state of war" with South Korea in its latest escalation of rhetoric against its southern neighbour and the US.

A statement promised "stern physical actions" against "any provocative act".

As Lucy Williamson reports from Seoul, the situation is very unpredictable and people are worried about an accidental escalation that comes out of this kind of war of words.