South Korean officials have issued their first formal response to recent moves by North Korea, labeling some of the North's recent statements "inappropriate." The exchange comes as high-level American and South Korean envoys warn time is running out in diplomacy to end North Korea's nuclear weapons programs. VOA's Kurt Achin reports from the South Korean capital.

South Korean Major-General Kwon Oh-sung has sent a radio message to his North Korean counterpart, reassuring Pyongyang the South remains committed to a key non-aggression agreement between the two sides.

However, the message rebukes the North for what it describes as recent "deliberate slander and fostering of tensions" which the South finds deeply regretful.

The message comes a day after North Korea's main official newspaper lashed out at South Korean President Lee Myung-bak, calling him a "traitor" and accusing him of disrupting North-South relations.

North Korea invaded South Korea in 1950. The two sides never formally ended the resulting war, which was halted by an armistice in 1953. Recent events have reminded the world how tense this peninsula remains.

Several days ago, North Korea warned it may turn the South into a "sea of ashes." That was a response to testimony by South Korea's joint chiefs of staff chairman that Seoul has contingency plans to preemptively strike North Korean nuclear weapons sites.

Earlier last month, North Korea expelled South Korean managers from a joint industrial park in the Northern city, Kaesong. South Korean media reports quote military officials who say South Korea has scrambled jets at least ten times since President Lee's February inauguration, to respond to North Korean warplanes approaching the North-South border.

Mr. Lee is much firmer on the issue of North Korea's nuclear weapons than his predecessors. He says future North-South cooperation is dependent on Pyongyang fulfilling its promises to end those weapons programs.

The chief American envoy to the multinational nuclear talks, Assistant Secretary of State Christopher Hill, is in Seoul to discuss the North's four-month delay in providing a nuclear declaration it said would be ready by the end of last year.

Hill warns the diplomatic process is "running out of time," and that North Korea, known formally as the DPRK (Democratic Peoples' Republic of Korea), must make a commitment.

"I think the problem is the DPRK needs to make this fundamental decision," he said. "Again, I think we have made progress on the declaration but, until we complete the declaration, we won't have succeeded."

Hill dismisses recent North Korean rhetoric against the South as "entirely propagandistic" and directed "entirely at domestic audiences." He says the comments will have little impact on the multinational nuclear diplomacy.