China is leading a chorus of condemnation of North Korea's purported nuclear test.
The Chinese government calls Monday's reported test "brazen" and says it resolutely opposes North Korea's actions. Beijing is calling on Pyongyang to return to stalled six-party nuclear disarmament talks.
China is one of North Korea's few allies and has previously responded to its neighbor's nuclear threats in measured tones. Beijing's statement Monday is the strongest reaction it has made on the issue since Pyongyang walked out of talks last year.
Japan quickly set up a task force Monday to deal with what it considers a threat to regional stability.
Japanese Prime Minister Shinzo Abe is in Seoul for talks with South Korean President Roh Moo-hyun, mainly to discuss the nuclear issue.
South Korea's Yonhap news agency says Mr. Abe called North Korea's reported nuclear test "unpardonable" after he landed in Seoul Monday.
Some information for this report provided by AP, AFP and Reuters.