SEOUL, South Korea — South Korea's president urged North Korea to show responsibility for two deadly attacks last year, ahead of looming defense talks between the divided countries.Lee Myung-bak also said in a televised panel debate Monday he can meet North Korean leader Kim Jong Il if the North changes its behavior and exhibits sincerity.Lee said that North Korea has a "good" chance to show that it's willing to change its behavior.The Koreas have agreed to hold a preliminary meeting to prepare for higher-level defense talks aimed at easing hostility on the peninsula, though they haven't set a date for the meetings.Tension spiked after the North's artillery bombardment of a South Korean island in November and the sinking of a warship last March.