Seoul
(AFP) --- North Korea said Wednesday it had carried out a
"successful" hydrogen bomb test, a claim that -- if true --
massively raises the stakes over the hermit state's banned nuclear
programme.
International condemnation was swift with neighbours South Korea and
Japan decrying a gross violation of UN Security Council resolutions,
while the White House said it was still studying the precise nature
of the apparent test and vowed to "respond appropriately".
"The
republic's first hydrogen bomb test has been successfully performed
at 10:00 am (0330 GMT)," North Korean state television
announced.
"With
the perfect success of our historic H-bomb, we have joined the rank
of advanced nuclear states," it said, adding that the test was
of a miniaturized device.
A
hydrogen, or thermonuclear bomb, uses fusion in a chain reaction that
results in a far more powerful explosion than the fission blast
generated by uranium or plutonium alone.
Last
month, North Korean leader Kim Jong-Un suggested Pyongyang had
already developed a hydrogen bomb.
The claim was questioned by international experts and there was
continued skepticism over Wednesday's test announcement.
-
Scepticism over H-bomb -
"The
seismic data that's been received indicates that the explosion is
probably significantly below what one would expect from an H-bomb
test," said Australian nuclear policy and arms control
specialist Crispin Rovere.
"So
initially it seems to be that they've successfully conducted a
nuclear test but unsuccessfully completed the second-stage hydrogen
explosion," Rovere said.
Bruce
Bennett, a senior defence analyst with the Rand Corporation, was
equally unconvinced.
"This
weapon was probably the size of the US Hiroshima bomb but this was
not a hydrogen bomb," Bennett told the BBC.
"The
bang they should have gotten would have been 10 times greater than
what they got," he added.
The
test, which came just two days before Kim Jong-Un's birthday, was
initially detected by international seismology centres as a
5.1-magnitude tremor next to the North's main Punggye-ri nuclear test
site in the northeast of the country.
Most experts had assumed Pyongyang was years from developing a
thermonuclear bomb, while assessments were divided on how far it had
gone in mastering the technology to miniaturise a warhead so that it
fits on a ballistic missile.
Whether
an H-bomb or not, it was North Korea's fourth nuclear test and marked
a striking act of defiance that flew in the face of enemies and
allies alike who have warned Pyongyang it would pay a steep price for
moving forward with its nuclear weapons programme.
-
Challenge to UN, Obama -
The
three previous tests in 2006, 2009 and 2013 triggered waves of UN
sanctions. Their failure to
prevent a fourth detonation will place
the Security Council under intense pressure to take more drastic
action this time around.
It
throws down a particular challenge to US President Barack Obama, who,
during a visit to South Korea in 2014, lashed North Korea as a
"pariah state" and vowed sanctions with "more bite"
if Pyongyang went ahead with another test.
White House National Security Council spokesman Ned Price said he
could not confirm the H-bomb claim, but promised the US would
"respond appropriately to any and all North Korean
provocations".
South
Korea "strongly condemned" the test and warned Pyongyang
that it would be made to "pay the price" for ignoring
international opinion.
Japanese Prime Minister Shinzo Abe called it a "serious threat"
to Japan and a "grave challenge" to nuclear
non-proliferation efforts.
-
China key player -
The
response of China, North Korea's economic and diplomatic patron, will
be key. Beijing has restrained US-led allies from stronger action
against Pyongyang in the past, but has shown increasing frustration
with its refusal to suspend testing.
But
China's leverage over Pyongyang is mitigated, analysts say, by its
overriding fear of a North Korean collapse and the prospect of a
reunified, US-allied Korea directly on its border.
China
has been pushing for a resumption of six-party, aid-for-disarmament
talks on North Korea, insisting that engagement with Pyongyang is the
only way forward.
The
six-party process, involving the two Koreas, the United States,
China, Japan and Russia, has been in limbo since 2007 and Pyongyang's
decision to move ahead with a fourth test has almost certainly
hammered the final nail in its coffin.
After its last nuclear test in 2013, the North restarted a plutonium
reactor that it had shut down at its Yongbyon complex in 2007 under
an aid-for-disarmament accord.
The Yongbyon reactor is capable of producing six kilograms (13
pounds) of plutonium a year -- enough for one nuclear bomb.
Pyongyang
is currently believed to have enough plutonium for as many as six
bombs, after using part of its stock for at least two of its three
atomic tests to date.
It is still unclear whether the 2013 test used plutonium or uranium
as its fissile material.
