Chief nuclear envoys of South Korea and China discussed North Korea’s nuclear programs in Beijing on Thursday, a day after Pyongyang dealt a setback in resuming international peace negotiations by walking out on Seoul during their defense talks.

Two days of inter-Korean preliminary military talks at a border village ended Wednesday after delegates from Pyongyang abruptly left the room, saying they no longer wanted to talk about the two deadly attacks North Korea apparently conducted against Seoul last year.

Heading to China for talks with his Chinese counterpart Wu Dawei, Seoul’s top nuclear envoy Wi Sung-lac said he will “mainly talk about the issue of bringing North Korea’s uranium enrichment program to the U.N. Security Council.”

North Korea unveiled a new, sophisticated uranium enrichment facility to outside experts in November, indicating its ongoing nuclear ambitions. Uranium, if highly enriched, can be used to make weapons, providing the communist state with an additional way of making atomic bombs after its existing plutonium-based program.

Seoul and Washington have been calling for stronger international condemnation of the program, claiming it violates the U.N. resolution as well as Pyongyang’s own pledge made during the 2005 six-nation talks to disarm.

China, North Korea’s last-remaining ally and major financial supporter, has been reluctant to bring the case to the U.N., although it officially acknowledged the program as “concerning” during last month’s presidential summit with Washington. Beijing is a veto-holding permanent member of the U.N. Security Council.

Wi said he will also be briefing the Chinese officials about the recent colonel-level talks with Pyongyang.

“Efforts toward dialogue (with North Korea) will continue,” he said.

The failed inter-Korean dialogue is a setback in resuming the stalled six-party talks North Korea has had with the South, the U.S., Japan, China and Russia since 2003. Hoping to rejoin the negotiations it walked from at the end of 2008, Pyongyang has been upping peace gestures toward Seoul, acknowledging inter-Korean dialogue as an essential step toward the resuming of larger-scale peace talks.

The inter-Korean military talks came months after North Korea bombed a South Korean border island and torpedoed a Seoul warship last year, the two incidents Pyongyang still refuses to admit fault or apologize for.

South Korea wanted to include an explicit North Korean apology for the two military provocations in the agenda for the higher-level defense talks. The North Korean delegates, however, didn’t accept the request, denying their military’s role in the incidents, Seoul officials said.

Washington called North Korea’s abrupt walkout a “missed opportunity” to demonstrate its sincerity and willingness to engage in any kind of dialogue.

“It is an important opportunity for North Korea to demonstrate its sincerity and willingness to engage in dialogue, and understand that the one delegation walked out today,” U.S. State Department spokesman P.J. Crowley said. “Clearly, having North Korea walking out puts them in the category of a missed opportunity.”

Amid the recent developments on the Korean Peninsula, three U.S. senators including John McCain have officially asked Secretary of State Hillary Clinton not to “rush into the six-party talks,” according to news reports.

The senators said the multinational aid-for-denuclearization talks should not restart until North Korea puts into action its willingness to disarm and make actual efforts to make peace with South Korea, reports said, citing a written statement that was sent to Clinton.

By Shin Hae-in and news reports  (hayney@heraldcorp.com)