South Korean President Lee Myung Bak says a new era in inter-Korean relations can be opened if North Korea shows sincerity.

In a nationally televised New Year's address Monday, Mr. Lee said there is a new opportunity on the Korean peninsula

as the young son of the late Kim Jong Il takes power as Supreme Commander of the North Korean military and ruling party leader after Mr. Kim's death last month.

But Mr. Lee also warned that South Korea will respond sternly to any provocation from the North.

On Friday, North Korea's powerful National Defense Commission said that there would be no policy changes under Kim Jong Un.

Tensions between the two Koreas have been high since Seoul accused Pyongyang of sinking a warship near the disputed sea border, known as the Northern Limit Line in March 2010. Forty-six South Korean sailors were killed in the attack.

Relations worsened after the North bombarded South Korea's Yeopyeong island in November 2010, killing four people.