North Korea announced on Wednesday it had successfully carried out its first hydrogen bomb test, a development that, if confirmed, would marking a stunning step forward in its nuclear development.
"The republic's first hydrogen bomb test has been successfully performed at 10:00am on January 6, 2016, 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 announcer said, adding that the test was of a "miniaturised" device.
The surprise test was personally ordered by North Korean leader Kim Jong-Un and came just two days before his birthday.
Only last month, during remarks made during an inspection tour, Kim had suggested Pyongyang had already developed a hydrogen bomb -- although the claim was greeted with
scepticism by international experts.
A hydrogen, or thermonuclear device, uses fusion in a chain reaction that results in a far more powerful explosion.
"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," the TV announcer said.
The announcement will leave the international community scrambling to verify the accuracy of the North's claims.
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 device that could fit on a ballistic missile.
While vowing to stick by a no-first use policy, Wednesday's statement said Pyongyang would continue to pursue an advanced nuclear strike capability.
"As long as the vicious anti-North policy of the US persists, we will never stop development of our nuclear programme," it said.
Earlier in the day, a 5.1 magnitude tremor was detected close to North Korea's nuclear test site, triggering concerns that Pyongyang had conducted a fresh atomic explosion.
The US Geological Survey said the epicentre of the quake was in the northeast of the country, some 50 kilometres northwest of Kilju city, placing it right next to the Punggyeri nuclear test site.
The “unusual” seismic activity near a “known” North Korean nuclear site seems to be of artificial origin and could be the sign of a possible nuclear test, Yonhap reported.
"The Foreign Ministry is currently holding a meeting presided over by the minister to immediately determine the situation following the reports," a ministry official said, according to the South Korean news agency.
The Japanese government said that an earthquake recorded in North Korea might have been caused by a nuclear test.
"Considering past cases, there is the possibility that this might be a nuclear test by North Korea," Chief Cabinet Secretary Yoshihide Suga, the government's top spokesman, said at a regular briefing, adding that Tokyo was analysing the situation.
Similar seismic activity in roughly the same area was recorded on February 12, 2013, prior to North Korea claiming its third successful underground nuclear test.
(With agenices input)