Updated

A U.S. envoy vowed to muster "maximum international pressure" on North Korea on Saturday, as a South Korean negotiator visited the communist state to urge it to abandon its nuclear weapons program.

U.S. Assistant Secretary of State James Kelly, speaking after meetings with Chinese and South Korean officials, said no timetable was set in the campaign to pressure North Korea to abandon its nuclear program.

Kelly, however, stressed that the isolated, impoverished North's best way to resume dialogue with Washington to improve ties and win badly needed aid is to give up the program that violated a 1994 agreement with the Washington.

"The United States is focused now on consultations with friends and allies and we hope to bring maximum international pressure on North Korea to abandon its nuclear weapons ambitions," Kelly said at a news conference after meeting South Korean Foreign Minister Choi Sung-hong and key national security advisers.

On Wednesday, Washington said North Korea admitted having a nuclear weapons program in violation of a 1994 agreement the two countries signed in Geneva. The admission came at Oct. 3-5 talks in Pyongyang, when Kelly confronted his North Korean counterparts with evidence of a program to enrich uranium for nuclear weapons.

Kelly flew to Seoul early Saturday from Beijing where he and Undersecretary of State John Bolton held two lengthy meetings with Chinese officials about the North's nuclear program.

Kelly planned to travel to Japan on Sunday.

"The Chinese made it very clear that they strongly oppose any nuclear weapons on the Korean peninsula," Kelly said. "I find that to be a very credible statement."

The U.S. envoy traveled to North Korea on Oct. 3-5, when communist negotiators admitted to a secret nuclear program after Kelly confronted his North Korean counterparts with evidence of a program to enrich uranium for atomic bombs.

South Korean Unification Minister Jeong Se-hyun arrived in the North's capital, Pyongyang, Saturday with a 48-member delegation for three days of talks.

"I will have straight talk about the nuclear issue," he said before leaving.

Both Koreas had agreed earlier to use the latest round of Cabinet-level talks to promote reconciliation on the divided Korean peninsula. Now Jeong says his most urgent task will be to gauge whether the North wants dialogue or confrontation.

The only official event scheduled for Saturday was a dinner hosted by North Korean Prime Minister Hong Song Nam, Seoul officials said.

South Korea says dialogue is the best way to deal with concerns about North Korea. News of North Korea's nuclear program threw the South's so-called "sunshine" policy of engagement into disarray, creating the perception that the North has duped the United States and South Korea for years.

South Korea and Japan, two key U.S. allies in Northeast Asia, are most vulnerable to North Korea's arsenal of weapons.

In Japan, a major newspaper reported Saturday that the government may ask that a U.S.-led consortium temporarily stop construction on light-water nuclear reactors in North Korea as a result of Pyongyang's admission.

Chief Cabinet Secretary Yasuo Fukuda will discuss the issue with Kelly, according to Japan's largest daily, the Yomiuri, which cited unidentified government sources.

Under the 1994 agreement, North Korea pledged to dismantle its nuclear weapons program in return for construction of two light-water reactors, financed mostly by South Korea and Japan. As part of the deal, the United States also provides North Korea with 500,000 tons of heating oil annually.

When asked whether the United States and allies may scrap the 1994 deal, Kelly said: "No decisions have been made on any next steps."

But he said the situation now "is not a replay of 1993 and 1994," indicating that Washington will be much tougher now.

Secretary of Defense Donald H. Rumsfeld said he believed the North Koreans already have a "small number" of nuclear weapons.

North Korea has been silent about its program and the international uproar it has triggered.