South Korea’s president vowed on Monday not to let North Korea “covet even an inch of our territory.” But he also opened the door to possible peace talks, saying North Korean disarmament could lead to South Korean economic aid.

Lee Myung-bak, addressing the country in a New Year’s speech, said the November 23 shelling of Yeonpyeong Island, which killed four and has spiked fears of war, was a transformational event. Seoul, he said, would treat it as the United States did the September 11, 2001, terrorist attacks and “overhaul our defense posture.”

However, he said, “if the North exhibits sincerity, we have both the will and the plan to drastically enhance economic cooperation.” Washington and Seoul have demanded that the North fulfill past nuclear disarmament commitments before allowing the resumption of stalled international aid-for-disarmament talks.

Still, the overwhelming focus of Lee’s comments on North Korea was a tough promise to improve South Korea’s defences and to hit back hard if attacked again.

“The situation before and after the provocation against Yeonpyeong Island cannot be the same,” Mr. Lee said. “Any provocation that would pose a threat to our lives and property will not be tolerated. Such provocations will be met with stern, strong responses.”

Mr. Lee was severely criticized for acting too slowly and too weakly after the shelling near the Koreas’ disputed western sea border - the North’s first attack on a civilian area since the 1950-53 Korean War. His government has responded by replacing the defence chief, strengthening security and pushing to deploy additional troops and weaponry to Yeonpyeong, which lies just seven miles (11 kilometers) from North Korean shores.

After the September 11 terrorist attacks, the United States “went back to the drawing board to devise new security and national strategies, because the safety and security of its people had come under threat,” Mr. Lee said.

“The shelling of Yeonpyeong Island also served as an opportunity for us to reflect on our security readiness and overhaul our defence posture,” he said. “There cannot be any delay in establishing security measures.”

Despite his strong words, Mr. Lee also said peace between the two Koreas is still possible. “The door for dialogue is still open,” he said.

Under Mr. Lee’s conservative administration, relations between the two Koreas have deteriorated as he reversed policies of earlier liberal-leaning administrations he saw as rewarding aggression.

Since taking office in early 2008, Lee has halted unconditional aid to the impoverished North and linked South Korean assistance to progress in North Korea’s disarmament efforts. That stance enraged Pyongyang, which cut off reconciliation talks and branded Lee “human scum” and a traitor to Korean reunification.

Tensions on the Korean peninsula are often high - the countries remain technically in a state of war because their 1950s war ended in a truce, not a peace treaty. But the North’s November shelling and subsequent South Korean military live-fire drills on Yeonpyeong and near the Koreas’ tense land border have put the region on edge and fired fears of renewed violence.

The North attacked Yeonpyeong, killing two civilians and two marines, after warning the South not to conduct live-fire drills there. North Korea claims the waters around Yeonpyeong as its own territory, refusing to recognize the maritime boundary drawn in 1953 by the United Nations without consulting with the North.

Mr. Lee’s speech came two days after North Korea issued its own New Year’s message. Pyongyang called for better ties and the resumption of joint projects with South Korea. It also reiterated its commitment to ridding the peninsula of atomic weapons and warned that a war would trigger a “nuclear holocaust.”

Meanwhile, the United States, which has about 28,000 troops in the South, is pushing ahead with diplomacy meant to find a way to ease tensions.

President Barack Obama’s top envoy on North Korea, Stephen Bosworth, and Sung Kim, the U.S. envoy to stalled nuclear disarmament talks, are to arrive in Seoul on Tuesday and then travel on to Beijing and Tokyo later this week. U.S. Defense Secretary Robert Gates is planning a visit to Seoul next week.

And on January 19 Chinese President Hu Jintao will be feted in Washington by Mr. Obama with a state dinner. China is the North’s only major ally and main benefactor, and the Hu-Obama meeting will be closely watched to see if any diplomatic breakthrough can be made.

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