North Korea says it has successfully tested a miniaturised hydrogen bomb which, if confirmed, would be its fourth nuclear test since 2006.

It came after a 5.1 magnitude quake was detected close to its nuclear test site at Punggye-ri, indicating a test may have been conducted.

This is North Korea's first claim to have tested a hydrogen bomb which is more powerful than a basic atomic bomb.

International experts have cast doubt over the North's nuclear capabilities.

Suspicion of an underground test was first raised after the US Geological Survey said the epicentre of the quake - detected at 10:00 Pyongyang time (01:30 GMT) - was in the north-east of the country, some 50km (30 miles) from Kilju city, near Punggye-ri.

Then in a surprise announcement, a newsreader on North Korean state TV said: "The republic's first hydrogen bomb test has been successfully performed at 10:00 am on January 6, 2016."

There has been no independent verification of this.

Last month, North Korean leader Kim Jong-un said Pyongyang had developed a hydrogen bomb, although many experts were sceptical.

If confirmed, it would mean Pyongyang is intent on pursuing its nuclear programme with little regard for the major political and diplomatic costs that will inevitably accompany this unwelcome development, says Dr John Nilsson-Wright of Asia Programme at Chatham House.

Analysis: Stephen Evans, BBC Korea correspondent
North Korean leader Kim Jong-un was shown attending an apparent submarine missile test last year

This test was apparently a hydrogen bomb, a step up in destructive power from the plutonium used in previous tests. It gives more explosive power for a lighter weight.

After the test in 2013, there was widespread condemnation. The UN Security Council held an emergency meeting at which its members, including China, "strongly condemned" the test. Similar outrage is expected this time. Prime Minister Abe of Japan has said this fourth test was a "serious threat to the safety of his nation".

On top of any fourth nuclear test, North Korea also appears to have tested a submarine-launched missile. The ability to launch missiles from submarines would change the whole calculation of military response because warning times of an attack on, for example, the West Coast of the United States would be much shorter.

Before the test, North Korean state media said the country "deserved to hold nuclear weapons... to counter nuclear threats by the US".

Experts believed before the fourth test that North Korea was still some years from being able to hit a target with a nuclear bomb delivered by a missile. But it is crystal clear that it is absolutely determined to be able to do so. It is also clear that it is improving its abilities rapidly.

How advanced is North Korea's nuclear programme?

North Korea's nuclear tests
Hours before the seismic activity, South Korean media reported that Pyongyang had test-fired a ballistic missile from a submarine in late December. It is unclear whether the test was successful or not.

In May last year, North Korea claimed it had successfully launched a missile from a submarine.

Strong reaction started pouring in after the North Korean announcement of the hydrogen bomb test, with South Korea saying it was a serious challenge to global peace and a violation of UN Security Council resolutions.

The Japanese Prime Minister Shinzo Abe said it was a threat to Japan's safety and could not be tolerated.

The US called on North Korea to abide by its international commitments and obligations saying it would respond to provocations.

After previous tests, the international community has responded with economic and political sanctions.

What is a hydrogen bomb?
A weapon energised by the nuclear fusion of hydrogen isotopes in a chain reaction, developed in 1952 by the United States

Also known as a thermo-nuclear bomb, it is much more powerful than a basic atomic bomb and has less radioactive fallout

Unlike an atomic bomb, powered by nuclear fission, a hydrogen bomb is powered by the fusion of lighter elements into heavier elements

Such bombs can be as small as a few feet long and can fit in warheads of ballistic missiles


North Korea and nuclear weapons
October 2002: North Korea first acknowledges it has a secret nuclear weapons programme

October 2006: The first of three underground nuclear explosions is announced, at a test site called Punggye-ri

May 2009: A month after walking out of international talks on its nuclear programme, North Korea carries out its second underground nuclear test

February 2013: A third nuclear test takes place using what state media calls a "miniaturised and lighter nuclear device"

May 2015: Pyongyang claims to have tested a submarine-launched missile, which are more difficult to detect than conventional devices

January 2016: North Korea says it has successfully tested a hydrogen bomb.

mazeltov:
North Korea never tested any Hydrogen bomb!!

YorubaParapo:


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