A senior South Korean official indicated Saturday that the country was "closer to finding an answer" that would resolve the U.S.-North Korea nuclear stalemate.
Meanwhile, Pyongyang's rhetoric was not subsiding, with the communist nation's state-run news agency KCNA calling the situation "serious and unpredictable."
Seoul's three-stage proposal is expected to be the centerpiece of a joint strategy conference between U.S., South Korea and Japan in Washington next week. Deputy Foreign Minister Lee Tae-shik left for Washington immediately following a South Korean National Security Council meeting at which the proposal was fine-tuned.
The Saturday edition of South Korea's Munhwa Ilbo afternoon newspaper outlined the government's mediation proposal. It includes a U.S. guarantee of North Korea's security and continued oil supply in return for an end to Pyongyang's nuclear weapons program. There are also provisions for international economic assistance for the beleaguered communist state, as well as a multinational security guarantee involving China and Russia.
Seoul's diplomatic offensive underlines its new drive to play the mediator between the United States, a key ally, and neighboring North Korea, its erstwhile enemy, and thus take a more assertive role in relations with its northern neighbor. But brokering a deal that would require concessions from both Washington and Pyongyang will not be easy.
The United States refuses to talk until the North scraps its nuclear weapons programs. And North Korea insists Washington must take the first step by signing a nonaggression pact promising not to attack the isolated country.
"There is no reason why the U.S. should not accept the proposal, the best way for peaceful solution," the North's state-run news agency said.
In past crises with the North, Seoul played a subordinate role to the United States. Now many South Koreans want their government to help chart the course of talks and assume more equal footing with Washington.
Being heard out by the United States is also seen as soothing rocky relations with South Korea amid rising public resentment over the 37,000 U.S. troops based here.
"The United States will be able to save a major strategic partnership by redefining South Korea's role in seeking a peaceful solution in this diplomatic maze," The Korea Herald said in its Saturday editorial.
The trilateral meeting, scheduled to take place in Washington early next week, is part of the allies' regular forum for coordinating policy toward the communist North. This time they will focus on bringing North Korea's nuclear weapons programs under international controls.
The communist North alarmed the world in October by admitting to a U.S. envoy it had a secret uranium-based nuclear weapons program, in violation of a 1994 accord.
As punishment, the United States and its allies halted oil supplies promised in the agreement. North Korea then announced it would reactivate its older plutonium-based nuclear program, saying it needs to restart a reactor to generate electricity.
The United States says the plutonium-based program, at the Yongbyon complex north of Pyongyang, could be used to build nuclear weapons. And Washington has indicated North Korea may already have two nuclear weapons and can build several more in short order.
One South Korean compromise being considered calls for the United States to resume oil shipments to North Korea, in return for it abandoning its uranium nuclear development, media reported Saturday, citing an unnamed government source.
Giving the North oil removes any justification for its restarting a nuclear complex to produce electricity, the reports said. A government spokesman could not immediately comment.
State Department spokesman Richard Boucher indicated Friday that Washington would not compromise. Arguing that North Korea already agreed to a nuclear freeze in 1994, he said, "We have no intention of sitting down and bargaining again."
In Beijing, the North's ambassador to China described the situation as "getting worse and worse," but indicated Pyongyang would welcome a mediator.
Meanwhile, Seoul has boosted efforts to rally international pressure on the North. South Korean diplomats are in Russia this weekend soliciting support, and they visited China earlier this week.
Moscow and Beijing, two of North Korea's traditional allies, want a nuclear-free Korean Peninsula. But so far, they have stopped short of declaring that they will aggressively pressure the North to give up its weapons programs.
Russian deputy foreign minister Alexander Losyukov said Saturday that both the United States and North Korea should search for a solution in a "calm and constructive way," the ITAR-Tass news agency reported.
"Threats and sanctions are counterproductive," he said.
Alexander Vershbow, the U.S. ambassador to Russia, welcomed Moscow's mediation.
"We think Russia has significant influence in Pyongyang and we are hoping that by working together we can persuade the North Koreans to pull back from the brink and to come back into compliance with their obligations not to develop nuclear weapons," the Interfax news agency quoted Vershbow as saying.
After next week's talks in Washington, Assistant Secretary of State James Kelly heads to Seoul for discussions with South Korean President-elect Roh Moo-hyun.
Roh intends to unveil his own compromise plan in hopes the crisis can be defused before he takes office Feb. 25.
South Korea must carefully juggle diplomacy between the United States, its key defense ally and largest trading partner, and North Korea, which has agreed to a series of joint projects — including reunions of families separated by the Korean War — which have helped ease Cold War mistrust on the peninsula.
The North and South have remained divided since the end of the 1950-53 Korean War, which ended not in a peace treaty but an armistice.
The Associated Press contributed to this report.