North Korea in new threat to South

North Korea threatened today to enlarge its nuclear arsenal and mercilessly attack South Korea and the US, as the allies prepared to start annual joint military drills which the North says are a rehearsal for an invasion.

North Korea routinely issues similar threats against South Korea and the US over any joint military drills.

The latest warning, however, could rekindle tensions on the Korean peninsula which sharply rose last year after two deadly incidents blamed on the North.

North Korea fired artillery at a front-line South Korean island in November, killing four people.

The barrage came eight months after the sinking of a South Korean warship which killed 46 sailors.

North Korea has denied firing a torpedo at the ship.