- South Korea, China, and Japan to hold emergency meetings.
- Fourth nuclear test in North Korea since 2006.
- Japanese PM Shinzo Abe condemns test.
UPDATE: NORTH Korea's official media agency has released a statement in four languages to explain today's hydrogen bomb detonation.
In the Korean Central News Agency's (KCNA) "H-bomb Test" article, available in Korean, English, Chinese and Japanese, the government applauds itself for "performing eye-catching miracles".
They say the bomb was a measure of self-defence to "protect the sovereignty of the country and the vital right of the nation from the ever-growing nuclear threat and blackmail by the US-led hostile forces and to reliably safeguard the peach on the Korean Peninsula and regional security."
The KCNA even go as far as to call the US a "gang of cruel robbers" who have worked to bring a nuclear disaster to North Korea.
After all "nothing is more foolish than dropping a hunting gun before herds of ferocious wolves", according to the Democratic People's Republic of Korea (DPRK).
"The DPRK, a responsible nuclear weapons state, will neither be the first to use nuclear weapons the NOR transfer relevant means and technology under any circumstances as already declared as long as the hostile forces for aggression do not encroach upon its sovereignty."
EARLIER: A MAGNITUDE 5.1 tremor detected today in North Korea has been confirmed to have been caused by a "successful" hydrogen bomb test.
"The republic's first hydrogen bomb test has been successfully performed ... based on the strategic determination of the Workers' Party," a state television news reader announced.
"With the perfect success of our historic H-bomb, we have joined the rank of advanced nuclear states.
"The latest test, completely based on our technology and our manpower, confirmed that our newly-developed technological resources are accurate and scientifically demonstrated the impact of our miniaturised H-bomb."
While a hydrogen bomb is much more powerful than an atomic bomb, it is also much harder to make. In a hydrogen bomb, radiation from a nuclear fission explosion sets off a fusion reaction responsible for a powerful blast and radioactivity.
North Korea is thought to have a handful of rudimentary nuclear bombs and has spent decades trying to perfect a multistage, long-range missile to eventually carry smaller versions of those bombs. After several failures, it put its first satellite into space with a long-range rocket launched in December 2012.
South Korean and Japanese officials have called emergency meetings.
Japanese Prime Minister Shinzo Abe told reporters the test was a violation of the U.N Security Council agreements.
"We absolutely cannot allow this, and condemn it strongly," said Abe.
Abe says he will take "strong action," work with other nations, the U.S., South Korea, China and Russia, as well as through the U.N.
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