South Korean president 'not afraid of war'

South Korea's president vowed relentless retaliation against North Korea if provoked again, saying he was not afraid of a war with the communist state.

The two Koreas have ramped up the rhetoric since North Korea shelled front-line Yeonpyeong Island near the tense western sea border last month, killing four South Koreans. Both sides accuse each other of provoking first.