South Korea formally announced Tuesday that it would join a U.S.-led effort to crack down on trafficking in weapons of mass destruction in response to North Korea's new nuclear test.
South Korean President Lee Myung-bak's government said it would join the 6-year-old Proliferation Security Initiative because of "the grave threat WMD and missile proliferation is posing to global peace," Foreign Ministry spokesman Moon Tae-young said.
The effort is aimed at interdicting shipments of weapons technology, a rare source of hard currency for North Korea, but Moon said the south would continue to uphold a shipping agreement with the north.
North Korea previously had protested any move by South Korea to join the initiative. There was no immediate response to Tuesday's declaration, but North Korea's state-run news agency said in April that any effort to join the initiative would be regarded as "a declaration of war."
The North Korea's nuclear bomb test -- its second -- reverberated around the world Monday, with the U.N. Security Council condemning it as a "clear violation" of international law and even Pyongyang's closest ally criticizing the exercise. China said North Korea "disregarded the opposition of the international community" to conduct the test.
"The Chinese government expresses firm opposition to this," a statement from Beijing's foreign ministry announced. It urged Pyongyang to return to the six-party talks aimed at dismantling its nuclear program, abide by its existing commitments and "cease any actions that might cause the situation to deteriorate further."
North Korea agreed in 2008 to scrap its nuclear weapons program, which it said had produced enough plutonium for about seven atomic bombs, in exchange for economic aid. But the deal foundered over verification and disclosure issues, and the North expelled international inspectors and announced plans to restart its main nuclear reactor.
At the United Nations, Security Council members took about an hour Monday to express their unanimous condemnation of the move. Russian Ambassador Vitaly Churkin called Monday's test "very serious" and said it "needs to have a strong response."
In a statement authorized by the council members, Churkin said the test was a "clear violation" of previous resolutions calling for North Korea to avoid provocative steps such as nuclear weapons or missile tests. And U.S. Ambassador Susan Rice said Washington will seek "strong measures" against North Korea.
"The U.S. thinks that this is a grave violation of international law and a threat to regional and international peace and security," she said.
