North Korean President Lee Myung Bak has asked its nation to be united in the event of war.

In a radio show South Korean President Myung-bak told the whole country is at stake. He added: “If [we] are afraid of war, we can never prevent war.”

Four people were killed when North Korea shelled Southern island of Yeonpyeong. Since then North Korea and South Korea relations has been simmering.

Lee government came under certain criticism of being weak after the Yeonpyeong attack.

Since then it has replaced its Defence Minsiter and harped on series of military exercises. The North has not retaliated so far but has vowed a sacred war against the South Korea.

Pyongyang denies South claim of sinking its warship. Instead North Korea accuses South of shelling which dropped shell in its territory in, retaliation of which North Korea shelled Yeonpyeong.

In the end of the speech Lee said, he wanted peaceful unification of the country.