Shock as N. Korea reports nuclear test

North Korea announced today that it has successfully completed an underground nuclear test, as the secretive regime continues efforts to bolster its nuclear capabilities after a rocket test launch in April.

Hours later, the South Korean news agency Yonhap reported that North Korea also had test-fired a short-range missile. South Korea’s Foreign Ministry said it was checking the report.

The developments follow months of tension during which North Korea has repeatedly rejected international pleas to abandon its burgeoning nuclear program.

Analysts say Pyongyang was irate over criticism by the U.S., Japan and South Korea of its April rocket launch and has grown impatient at the lack of attention it has received from the Obama administration -- both possible motives for today’s action. North Korea had threatened to test another missile, or another nuclear device, unless the United Nations apologized for imposing new sanctions after that missile test, which Pyongyang said was a peaceful satellite launch.

The international community expressed shock at the new developments, which came as another blow to international efforts to dismantle the communist nation’s nuclear program. North Korea is thought to have enough weaponized plutonium to make more than half a dozen bombs, analysts say.

President Obama called the development “a matter of grave concern.”

“By acting in blatant defiance of the United Nations Security Council, North Korea is directly and recklessly challenging the international community,” he said. “. . . Such provocations will only serve to deepen North Korea’s isolation. It will not find international acceptance unless it abandons its pursuit of weapons of mass destruction and their means of delivery.”

Russia’s U.N. ambassador told Reuters news service that the Security Council would hold an emergency meeting today.

Five nations -- Russia, China, South Korea, Japan and the U.S. -- have been negotiating with North Korea on ending its nuclear weaponry program for years, but the rogue nation recently walked away from the so-called six-party talks.

The nuclear test came about 10 a.m. today, when seismologists from the U.S., South Korea and Japan reported earthquakes in a northeastern area, just a few miles from where North Korea conducted a nuclear test in 2006, according to wire reports.

The U.S. Geological Survey recorded a magnitude 4.7 tremor in the northeast, about 40 miles northwest of the city of Kimchaek.

Japanese officials also said they would seek redress at the U.N., Reuters reported. Japan will respond to North Korea’s nuclear test “in a responsible fashion,” said a Foreign Ministry spokesman attending a regional meeting in Vietnam.

“We are now aware of the news that the [North Korea] conducted a nuclear test for the second time, so we are certainly going to respond in a very responsible manner,” the spokesman, Kazuo Kodama, said. “Definitely we are going to respond, we have to, at the U.N. Security Council.”

In Seoul, stock markets tumbled at news of the nuclear test. South Korean President Lee Myung-bak called for an emergency session of the country’s security ministers in the underground bunker of the Blue House, the South Korean presidential mansion.

According to the North Korean news agency’s release, “The test will contribute to defending the sovereignty of the country and the nation and socialism and ensuring peace and security on the Korean peninsula and the region around it.”

The release added that the test was successful and was more powerful than its previous test.

“The current nuclear test was safely conducted on a new higher level in terms of its explosive power and technology,” the news agency reported. “The results of the test helped satisfactorily settle the scientific and technological problems arising in further increasing the power of nuclear weapons and steadily developing nuclear technology.”

Security experts today said they were awaiting the results of the strength of the North’s latest nuclear test.

Daniel Pinkston, North East Asia deputy project director for the International Crisis Group, a global security think tank, said that the previous North Korean nuclear test registered about 1 kiloton, a measure of the amount of the explosives involved.

Most tests by other nations have been in the 20 to 40 kiloton range, Pinkston said.

“We’re waiting to see what the yield [or strength] of the latest test was,” he said. “Apparently, the North Koreans had suggested to the Chinese that its test would be in the 4-kiloton range.”

The 2006 nuclear test was considered a failure by many analysts and North Korea may be trying to work out any design flaws in its current test, he added.

In April, North Korea announced that it had begun harvesting plutonium from spent fuel rods at its main nuclear plant.

Some South Korean analysts said they were not surprised by today’s test.

“This test was pretty predictable. North Korea has been ready for this event and told the whole world about it,” said Koh Yu-hwan, a Dongguk University professor of North Korea studies in Seoul.

He said that North Korean leader Kim Jong Il has been frustrated by a lack of progress with his desired one-on-one talks with the Obama administration.

“For the moment, it seems that North Korea internally agreed to strengthen its nuclear deterrence,” he said.

Analysts say the nuclear test also is the latest move in Kim’s strategy to boost his position at home.

A successful nuclear program would defy the global community and win support for his chosen successor from the nation’s hard-line military forces, said to number more than 1 million.

The North Korean test came as South Korea mourned the suicide of former President Roh Moo-hyun, who had been under investigation on suspicion of accepting bribes during his term in office.

Experts doubted whether the timing of the nuclear test was moved up to take advantage of a distracted South Korea.

“This isn’t just something you can prepare for overnight -- there’s a long lead-up time,” said Pinkston.

“Everything else had to be in place”

--

john.glionna@latimes.com

Times staff writer Paul Richter in Washington and Ju-min Park of The Times’ Seoul Bureau contributed to this report.