“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.
Suspicions over a possible nuclear test — Pyongyang’s fourth — were first raised by seismologists who said they had detected a 5.1 magnitude tremor next to its main atomic test site in the northeast of the country.
The website of the China Earthquake Network Centre described the seismic activity as a “suspected explosion”, while the Japanese government said there was a strong possibility that “this might be a nuclear test”.
The US Geological Survey said the epicentre of the quake — detected at 10:00 am Pyongyang time (0130 GMT) — was in the northeast of the country, some 50 kilometres (30 miles) northwest of Kilju city, placing it right next to the Punggye-ri nuclear test site.
Any confirmation of the test will trigger widespread international condemnation of North Korea, which has already conducted three nuclear tests in 2006, 2009 and 2013 — all at Punggye-ri.
South Korea on Wednesday “strongly” condemned North Korea’s shock announcement that it had carried out a hydrogen bomb test and vowed to take “all necessary measures” to penalise its nuclear-armed neighbour.
“We strongly condemn that North Korea carried out a fourth nuclear test in clear violation of UN Security Council resolutions, despite repeated warnings from us and the international community,” said a government statement read on television by the deputy head of the National Security Council (NSC).
President Park Geun-Hye had convened an emergency meeting of the NSC as soon as the test was announced.
The United States slammed North Korea’s “provocations” and vowed to respond appropriately while stressing it could not confirm the hermit state’s claims that it had carried out a hydrogen bomb test.
“While we cannot confirm these claims at this time, we condemn any violation of UNSC (United Nations Security Council) resolutions and again call on North Korea to abide by its international obligations and commitments,” White House National Security Council spokesman Ned Price said in a statement late Tuesday.
The United States, he added, would “respond appropriately to any and all North Korean provocations.”