PUSAN, South Korea - North Korea stormed out of talks with South Korea on Thursday and Seoul froze food aid to its impoverished neighbour, as regional fissures over how to deal with Pyongyang's missile tests widened.
Pyongyang also appeared to have stood up to its closest ally, Beijing, which has sent a "friendship delegation" to North Korea.
"So far they don't seem to be interested in listening, much less doing anything," US Assistant Secretary of State Christopher Hill told reporters in Beijing. "I think the Chinese are as baffled as we are."
China and the United States have urged the reclusive communist state to return to six-party talks with South Korea, Japan and Russia on winding up its nuclear arms programme.
The negotiations stalled last November because Pyongyang objected to US financial sanctions based on accusations North Korea counterfeited US currency and trafficked drugs.
Bilateral ministerial talks in the South Korean city of Pusan broke down in acrimony on Thursday as Pyongyang's delegation walked out a day before they were due to end.
"The South side will pay a price before the nation for causing the collapse of the ministerial talks and bringing a collapse of North-South relations that is unforeseeable now," the delegates said in a statement before leaving for the airport.
They accused the South of acting as a "mouthpiece" for others at the talks, at which they had parried complaints about last week's missile launches and focused instead on economic cooperation and requests for aid.
Seoul said it had suspended the dispatch of food aid to the North until Pyongyang returns to the six-country talks.
Explaining at what point Seoul would consider a resumption of aid, a South Korean senior government official said: "I think it is the (North's) return to six-party talks."
Hill said he was confident the United Nations would send a "very strong, very clear message" to Pyongyang over the barrage of missiles it test-fired on July 5. But there were still big differences among regional powers over the appropriate response.
China and Russia have introduced a UN Security Council resolution that urges North Korea to suspend its nuclear programme but avoids the mandatory weapons-related sanctions sought by Japan.
Japan said on Thursday it would still seek a Security Council vote on a resolution that would impose sanctions for the North Korean missiles, which splashed into the sea off its west coast.
Chief Cabinet Secretary Shinzo Abe said Japan and the United States had agreed to give China's diplomatic efforts a chance, but Tokyo would not wait forever for a Security Council vote.
"We can't be twisted around by any attempts to buy time to water down the strong resolve of the international community over the firing of the missiles," he said.
China's Foreign Ministry repeated calls for a diplomatic solution and urged members of the Security Council to craft a "cautious and measured response".
Earlier, it criticised Japan for "pouring oil on fire" for raising the issue of a pre-emptive strike on North Korea after the tests, warning it could seriously disrupt international efforts to defuse the crisis.
- REUTERSBy Jack Kim