North Korea said it detonated a nuclear bomb, hours after the Japanese and Chinese governments joined the United Nations Security Council in warning the communist country against proceeding with the test.
The test "was carried out under a scientific consideration and careful calculation," North Korea's official Korean Central News Agency said in its English-language release. It is the first time North Korea has announced a nuclear test.
South Korea's government raised its military alert level and the Finance Ministry said it would hold an emergency meeting at 3 p.m., as North Korea's actions were condemned internationally. China's government called it a "brazen" disregard of international opinion in a statement posted on the Foreign Ministry's Web site, while Japan called for "decisive action."
"We're working on gathering more information and are in the process of consulting with our allies in Japan to deal with this very grave situation," said Jeffrey Hill, a U.S. Embassy spokesman in Tokyo.
North Korea said on Oct. 3 it would conduct a nuclear test, without giving any indication of timing. Today's report means it now faces the prospect of the U.S. drafting a United Nations resolution that includes the threat of military action. The U.S. ambassador to the UN, John Bolton, on Oct. 4 pledged such a measure should North Korea detonate a nuclear weapon.
The yen, South Korea's won and Asian stocks fell.
Earthquake Detected
South Korea detected a 3.58 to 3.7 magnitude tremor in North Korea's town of Musudan-ri, Hwadae, in the North Hamkyong province on its east coast at 10:35 a.m., South Korea's presidential spokesman Yoon Tai Young told reporters in Seoul. South Korea is trying to determine if the tremor was caused by a nuclear test, Yoon said. Musudan-ri is the base from which Pyongyang launched its unsuccessful Taepodong-2 long-range ballistic missile of July 5. The U.S. Geological Survey also detected a tremor, it said on its Web site.
South Korean Prime Minister Han Myeong Sook will preside over an emergency meeting at the Finance Ministry at 3 p.m., to map out measures to minimize any negative impact on the South Korean economy, the ministry said in an e-mailed statement.
The United Nations Security Council's 15 member governments unanimously adopted a statement on Oct. 6 urging North Korea to abandon its plan to test a nuclear weapon and return to six- nation talks aimed at dismantling the Communist country's arms program. While no specific threats of UN action were included, the text said the council would "act consistent with its responsibility under the charter of the United Nations" if a test is conducted. China and Russia joined in the warning.
'Not Listening'
"North Korea, which once listened to China, now clearly isn't listening to China and is thumbing its nose at the Six Party process hosted by China. It also illustrates China no longer has such a big leverage over North Korea as it used to.
The reported test, which coincides with a visit by Japanese Prime Minister Shinzo Abe to Seoul, may also set off an arms race in the region similar to the nuclear proliferation in South Asia, where India detonated two devices in May 1998, followed in the same month by Pakistan's test of a bomb.
North Korea's threat as an exporter of weapons technology to terrorists or so-called rogue states would increase with a test, U.S. Defense Secretary Donald Rumsfeld said on Oct. 5.
'Known Proliferator'
"North Korea is a known proliferator of weapons technologies," Rumsfeld said. "They've announced they have nuclear weapons. People have to be concerned that a proliferating nation might proliferate weapons of that type."
The U.S. cannot accept a nuclear North Korea, Assistant Secretary of State Christopher Hill said on Oct. 4. Hill is the U.S. delegate to talks with North Korea involving China, Japan, South Korea and Russia to convince Kim Jong Il's regime to end its nuclear arms program.
"It's a statement of our policy, which is we don't think they should have nuclear weapons," Tony Snow, the White House press secretary, said at a briefing Oct. 5. "The Chinese agree, and the South Koreans agree, and the Russians agree and the Japanese agree. So all the parties to it, with one possible exception in the six-party talks, and that would be the North Koreans, agree."
Australian Prime Minister John Howard, speaking in parliament, said the test has "destabilized the region" and advocated "financial and travel sanctions, other trade restrictions and/or aviation restrictions."
"North Korea is very gravely mistaken if she thinks a nuclear test will improve that country's bargaining position," Howard said. "A strong international response is called for."
The U.S. said it couldn't immediately confirm a nuclear test by North Korea.
"We can't confirm independently, although we're aware of the reports," said Emily Lawrimore, a White House spokeswoman.
China's Role
A North Korean test may put pressure on China from the other parties in the talks to take a harsher stance toward the North, Japanese Foreign Minister Taro Aso said on Oct. 6. China is North Korea's closest ally.
"China has been the only country in the world willing to shield North Korea, but I wonder if China will be able to maintain a similar stance toward North Korea," Aso said. "Doing so, I believe, will be tough for China this time."
A test is likely to result in a complete breach in relations with China, said Koh Yu Hwan, professor of North Korean studies at Dongguk University in Seoul.
"This means the end of China-North Korea relations," he said. "Proof that North Korea has a working nuclear weapon will prompt Japan, South Korea and Taiwan to arm themselves with nuclear weapons. This will inevitably threaten China, and China won't stand for that."
North Korea agreed at a September 2005 session of the six- nation talks to abandon its nuclear program in return for energy and food aid and security guarantees.
Nuclear Weapons
The government said Oct. 3 it planned a nuclear test because of threats and sanctions by the U.S. The U.S. imposed sanctions a year ago over allegations of money-laundering and counterfeiting by North Korean companies.
North Korea may have produced as many as six nuclear weapons from spent reactor fuel, U.S. officials estimated in 2004, according to a Congressional Research Service report on its atomic arms program dated May 25 this year. The Institute for Science and International Security said in a June 26 report that North Korea may have enough plutonium to make as many as 13 nuclear weapons.
The country drew international condemnation when it tested seven missiles on July 5, including the Taepodong-2, which U.S. officials have said may be able to reach Alaska. The UN Security Council on July 15 condemned the tests and barred the country from receiving missile-related technology.
Sanctions
Japan imposed some sanctions on the country after the test of the missiles. Japanese officials have also suggested the government should consider whether Japan's pacifist constitution allows for a pre-emptive strike on North Korean missile bases.
North Korea, with a population of 23 million, has depended on outside aid since the 1990s, when more than a million people may have died from famine because of years of flooding, drought and economic mismanagement.
International food aid for North Korea reached 1.08 million tons last year, the world's second-largest amount after Ethiopia's 1.1 million tons, according to the UN Food and Agriculture Organization. South Korea sent 394,000 tons of food aid to North Korea last year.