The UN Security Council said Tuesday that it would start discussions on imposing new sanctions on North Korea after Pyongyang carried out a nuclear test, dpa reports
North Korea government confirmed that it "succeeded in the third underground nuclear test" at its northern facility, state-run Korean Central News Agency said.
The blast at 11:58 am (0258 GMT) was twice the size of the last North Korean nuclear test in 2009, the Comprehensive Nuclear-Test-Ban-Treaty Organization (CTBTO) said in Vienna, without providing an exact estimate of the yield.
The CTBTO said the blast occurred in the same remote north-east area as North Korea's previous nuclear tests in 2006 and 2009. While the explosive force was greater in the most recent blast, the seismic shock waves were comparable to the 2009 test.
South Korea's Defence Ministry estimated the explosive force of the weapon to be 6 to 7 kilotons (KT) of TNT, Yonhap news agency reported. By comparison, the bomb dropped on Hiroshima in 1945 had a strength of 13 to 16 kilotons.
The Security Council, after a meeting chaired by South Korean Foreign Minister Kim Sung-hwan at UN headquarters in New York, said it "strongly condemns" the test as a "clear threat to international peace and security" and to the Korean peninsula and North-East Asia.
Kim said the Security Council decided to begin work "immediately on appropriate measures" in a new UN resolution.
Kim said Seoul will cooperate closely with the international community to seek all necessary measures, including actions by the United Nations, in order to have North Korea abandon its nuclear ambitions. "North Korea will be held responsible for any consequences of this provocative act," Kim said.
Tuesday's disturbance measured magnitude 4.9, the United States Geological Survey (USGS) reported, whereas the previous blast registered magnitude 4.5.
US President Barack Obama called the test a "highly provocative act" that "undermines regional stability." China expressed "resolute opposition" to the test and its commitment to six-nation talks to end Pyongyang's nuclear programme.
Obama and South Korean President Lee Myung Bak telephoned later Tuesday to "to consult and coordinate" in response to the North Korean test, which they condemned, the White House said. The two presidents agreed to "work closely together" to impede North Korea's nuclear and ballistic missile programmes and prevent weapons proliferation, and Obama "unequivocally reaffirmed" US defense commitments to South Korea including the US nuclear umbrella.
German Foreign Minister Guido Westerwelle said "even more sanctions ... must now be considered" against North Korea for "its flagrant violation" of UN resolutions.
Chinese Foreign Minister Yang Jiechi summoned the North Korean ambassador and delivered a "stern message" and "strong dissatisfaction" with Pyongyang's nuclear weapons test, the Chinese Foreign Ministry said.
In Iran, which is entangled in a nuclear dispute with the UN, the Foreign Ministry said that "all nuclear weapons should be abolished, and no country should have such weapons."
South Korea's National Intelligence Service told a parliamentary committee that Pyongyang may follow up with another provocative measure - such as further nuclear tests or a long-range missile launch - especially if the UN Security Council takes punitive action, according to Yonhap.
Pyongyang said the test was part of defensive measures "in the face of the ferocious hostile act of the US, which wantonly violated (North Korea's) legitimate right to launch a satellite for peaceful purposes."
North Korea said the test was conducted "in a safe and perfect way on a high level with the use of a smaller and light A-bomb, unlike the previous ones yet with great explosive power."
A smaller warhead would improve the regime's ability to arm a missile. Bulky weapons and limited missile capability are considered limiting factors of Pyongyang's programme.
Weapons experts were watching to see whether North Korea has switched from plutonium to uranium, which is much easier to refine to weapons grade level in hidden locations, away from international monitoring.
Japan and South Korea ordered meetings of their national security councils, and Tokyo announced further sanctions against Pyongyang. Russia condemned the test and said it was evaluating the situation on its Sea of Japan coast near North Korea.
European Union foreign policy chief Catherine Ashton threatened "consequences" for Pyongyang, saying the bloc would work with international partners to find a "unified response."