N Korea warns war drills take region to 'brink of war'

North Korea has warned that joint military exercises by the US and South Korea this weekend may push the region to "the brink of war".

Tensions on the peninsula have continued to rise after artillery fire was heard from the North - although no shells landed on southern territory.

The latest explosions come three days after North Korean missiles killed four people on the South Korean land of Yeonpyeong.

From Seoul, Chris Hogg reports.