North Korea conducts powerful nuclear test
South reports launch of 3 missiles; atomic test likened to Hiroshima bomb
SEOUL, South Korea - North Korea carried out a powerful underground nuclear test Monday — much larger than one conducted in 2006 — in a major provocation in the escalating international standoff over its rogue nuclear and missile programs.
South Korea's Yonhap news agency said North Korea also test-fired a total of three short-range missiles after announcing the atomic test. The first liftoff, widely believed to be a cover for a test of its long-range missile technology, drew censure from the U.N. Security Council.
Pyongyang announced the test, and Russia's Defense Ministry confirmed an atomic explosion at 9:54 a.m. (0054 GMT) in northeastern North Korea, estimating the blast's yield at 10 to 20 kilotons — comparable to the bombs that flattened Hiroshima and Nagasaki.
North Korea, incensed by the condemnation of the April 5 rocket launch, had warned last month that it would restart it rogue nuclear program, conduct an atomic test and carry out long-range missile tests.
On Monday, the country's official Korean Central News Agency said the regime "successfully conducted one more underground nuclear test on May 25 as part of measures to bolster its nuclear deterrent for self-defense."
The regime also test-fired a short-range, ground-to-air missile Monday from the same northeastern site where it launched a rocket last month, the Yonhap news agency reported, citing unnamed sources.
Hours later, it test-fired two more short-range missiles, according to the South Korean news agency.
Yonhap did not provide further details and did not name its source.
South Korea's military declined to confirm the reports, saying it does not comment on intelligence matters.
U.S. President Barack Obama said a nuclear test would constitute an act of "blatant defiance" of the U.N. Security Council and a violation of international law, and would only further isolate North Korea.
North Korea's claims "are a matter of grave concern to all nations," he said, calling for international action in a statement from Washington. "North Korea's attempts to develop nuclear weapons, as well as its ballistic missile program, constitute a threat to international peace and security."
Japanese Prime Minister Taro Aso said the U.N. Security Council will meet at 4:30 p.m. Monday in New York (2030 GMT).
"If North Korea carried out a nuclear test, it would clearly violate U.N. Security Council resolutions," chief government spokesman Takeo Kawamura told reporters in Tokyo. "We will definitely not tolerate it."
South Korean President Lee Myung-bak called the test "a provocation that can never be tolerated," his spokesman Lee Dong-kwan said.
"The nuclear test is a serious threat to peace and security on the Korean peninsula, in Northeast Asia and in the world," the presidential office said in a statement.
South Korea, meanwhile, was grappling with the suicide two days earlier of Lee's liberal predecessor, Roh Moo-hyun, whose death prompted condolences from North Korean leader Kim Jong Il. Kim held a 2007 summit in Pyongyang with Roh, who championed reconciliation with North Korea.
Monday's atomic test was conducted about 50 miles (80 kilometers) northwest of the northern city of Kilju, Russian Defense Ministry spokesman Alexander Drobyshevsky said, speaking on state-run Rossiya television.
Kilju, in the northeastern province of North Hamgyong, is where North Korea conducted its first nuclear test in October 2006 in a surprise move that angered even traditional ally China and drew wide-ranging sanctions from the Security Council.
An emergency siren sounded in the Chinese border city of Yanji, 130 miles (200 kilometers) to the northwest. A receptionist at Yanji's International Hotel said she and several hotel guests felt the ground tremble.
North Korea boasted that Monday's test was conducted "on a new higher level in terms of its explosive power and technology of its control" than in 2006.
Ten to 20 kilotons would be many times more than North Korea managed in 2006. U.S. intelligence officials said the 2006 test measured less than a kiloton; one kiloton is equal to the force produced by 1,000 tons of TNT.
Russia checks radiation levels
Radiation levels in Russia's Primorye region, which shares a short border with North Korea, were normal several hours after the blast, the state meteorological office said.
In Vladivostok, a city of 500,000 about 85 miles (140 kilometers) from the Russian-North Korean border, translator Alexei Sergeyev said he wasn't concerned about the test and doesn't fear North Korea.
"Their nuclear program does not have military aims — their only aim is to frighten the U.S. and receive more humanitarian aid as a result," said Sergeyev, 24.
The reported test-fire of the short-range missile took place at the Musudan-ri launchpad on North Korea's northeast coast, Yonhap said. Sources described it as a ground-to-air missile with a range of 80 miles (130 kilometers).
Japan's coast guard had said Friday that North Korea warned ships to steer clear of waters off the coast near the launch site, suggesting Pyongyang was preparing for a missile test. Yonhap also had reported brisk activity along the northeast coast last week.
South Korean troops were on high alert but there was no sign North Korean soldiers were massing along the heavily fortified border dividing the two nations, according to an official at the Joint Chiefs of Staff headquarters in Seoul. He spoke on condition of anonymity, citing agency policy.
Two Koreas technically at war
The two Koreas technically remain at war because their three-year conflict ended in a truce, not a peace treaty, in 1953. Tensions have been high since conservative President Lee Myung-bak took office in Seoul in February 2008 saying Pyongyang must fulfill its promises to dismantle its nuclear program before it can expect aid.
North Korea is believed to have enough weaponized plutonium for at least a half-dozen atomic bombs. However, experts say scientists have not yet mastered the miniaturization needed to mount a nuclear device onto a long-range missile.
The 2006 test prompted North Korea's neighbors and the U.S. to push for a pact that would give Pyongyang 1 million tons of fuel oil in exchange for disabling its nuclear facilities.
North Korea signed the accord in February 2007 and began disabling its main nuclear reactor in Yongbyon that November. Pyongyang destroyed the Yongbyon cooling tower in June 2008 in dramatic show of its commitment to the process, but then abruptly halted the process weeks later over a dispute with Washington over how to verify its 18,000-page list of past atomic activities.
Talks hosted by Beijing in December failed to resolve the impasse, and North Korea abandoned the six-nation negotiations last month in anger over the U.N. condemnation of its rocket launch.
North Korea claims it launched the rocket to send a satellite into space; South Korea, Japan and other nations saw it as a way to test the technology used to launch an intercontinental ballistic missile, one capable of reaching the U.S.
The Security Council called the launch a violation of 2006 resolutions barring the regime from ballistic missile-related activity.