With tensions at boiling point on the Korean peninsula, state TV in the North says relations with the South have been irreparably damaged.
A defiant broadcast, illustrated with images of North Korean leader Kim Jong-il, insisted that Seoul provoked Tuesday’s attack by Pyongyang.
The North rained artillery shells on a South Korean island, killing two South Korean soldiers.
Authorities say the bodies of two civilians have also been found.
It was the heaviest attack since the Korean war ended in 1953.
Pyongyang says Seoul fired shells into its territory first. The South denies doing so but did fire in response to the North Korean strike.
Standing firmly behind Seoul, the US has sent an aircraft carrier group to Korean waters for what it says are pre-planned joint exercises. The US believes Pyongyang’s attack was an isolated action. The American military considers it is linked to the succession of the North’s leadership.