美韩日:必须就朝鲜核项目加紧对平壤施压

Top nuclear negotiators from the United States, South Korea and Japan agreed in a meeting Wednesday that they need to increase pressure and sanctions against North Korea while continuing diplomatic efforts to address the country's nuclear weapons program.

Sung Kim, the U.S. special representative for North Korea policy, said after the talks in Seoul that North Korea's nuclear intentions are clear. "We should be concerned regardless of the stage of their development," he said.

The meeting comes after new, but unverified, claims of nuclear advancements by North Korea, which has threatened for years to carry out a nuclear attack on the U.S., South Korea and Japan. The three nations were part of unsuccessful six-party disarmament talks to address North Korea's nuclear arsenal.

South Korean envoy Hwang Joonkook described the situation as uncertain and tense, saying Wednesday that North Korea continues to advance its program.

The U.S. and South Korean envoys are due to travel to Beijing to meet with their Chinese counterpart, as they continue working on a unified approach to North Korea.