North Korea successfully conducted an underground nuclear test on October 9, the Central News Agency of North Korea said. There is no threat of radioactive contamination as a result of the test, the agency reported.
The nuclear test was conducted on October 9 at 10:36 a.m. local time in the north-east of the country, South Korean Defense Ministry officials said. The underground nuclear blast triggered a 3.58 magnitude earthquake, the South Korean intelligence said.
A high-ranking officials of the US administration confirmed that North Korea had tested nuclear weapons. The official added that the US government had been warned about the imminent nuclear tests in North Korea. The Pentagon is currently trying to specify the technical description of the nuclear blast, Fox News said. North Korea warned the Chinese government about its intention to test nuclear weapons only 20 minutes before the blast. The government of China transmitted the warning to the governments of the USA, Japan and South Korea.
Japan believes that claimed nuclear test poses a serious danger to the Asian region and the world stability in particular.
Japanese Foreign Minister said Monday that he and his South Korean and U.S. counterparts agreed during a teleconference to work closely on a response to North Korea's claimed nuclear test. "If the test was true, it will severely endanger not only Northeast Asia but also the world stability," he said. "We will closely coordinate and firmly deal with the situation," Minister Taro Aso said.
The U.S. Geological Survey said it recorded a seismic event with a preliminary magnitude of 4.2 in northeastern North Korea that coincided with the country's announced nuclear test.
The Colorado-based agency was unable to tell whether the event was the result of an atomic explosion or a natural earthquake, USGS official Bruce Presgrave said.
"At this magnitude, we can't tell whether it's a small earthquake or something else, like an explosion," Presgrave said.
Australia also said there was seismic confirmation that North Korea conducted a nuclear test.
China, the North's closest ally, said Beijing "resolutely opposes" the North Korean nuclear test and hopes Pyongyang will return to disarmament talks.
South Korean presidential spokesman Yoon Tae-young said: "Our government will sternly react under the principle that it cannot tolerate the North's possession of nuclear weapons."
U.S. and South Korean officials could not immediately confirm that an actual test had occurred.
The U.N. Security Council was expected to discuss the reported North Korean test Monday, and the United States and Japan are likely to press for a resolution imposing additional sanctions on Pyongyang. The council last week issued a statement condemning plans for a test.
A resolution adopted in July after a series of North Korean missile launches imposed limited sanctions on North Korea and demanded the country rejoin international nuclear talks - a demand the North immediately rejected.
The North has refused for a year to attend international talks aimed at persuading it to abandon its nuclear ambitions. The country pulled out of the Nuclear Nonproliferation Treaty in 2003 after U.S. officials accused it of a secret nuclear program, allegedly violating an earlier nuclear pact between Washington and Pyongyang.
The North is believed to have enough radioactive material for about a half-dozen bombs, using plutonium from its main nuclear reactor located at Yongbyon, north of the capital Pyongyang, the AP says.
The North also has active missile programs, but it isn't believed to have an atomic bomb design small and light enough to be mounted on a long-range rocket that could strike targets as far as the U.S.
In Pyongyang, there were no signs of unusual activity Monday as North Koreans went about their lives as usual. The red flag with the yellow hammer, sickle and pen of the North's Korean Workers' Party draped buildings and lampposts to mark Tuesday's 61st anniversary of the party's founding, and there were no signs of heightened alert by security forces.
Although reported by the outside world by the North's official news agency, state TV had yet to begin its daily broadcasting so most North Koreans were unaware of the test.
The test came amid intense diplomatic efforts aimed at heading off the move.