The secretive totalitarian state announced it had carried out its first underground test of a hydrogen bomb earlier today. It was the country's fourth nuclear test since 2006.
New Zealand duty minister Sam Lotu-Iiga said the Government strongly condemned the North Korean test.
"New Zealand views North Korea's actions as highly provocative and irresponsible," he said.
"The test would run contrary to the recent efforts at dialogue on the Korean peninsula and flies in the face of the international community's calls for North Korea to abandon its nuclear weapon programmes and return to the Nuclear Non-Proliferation Treaty.
"This action also flouts UN Security Council resolutions which have demanded that North Korea not conduct any further nuclear tests.
An emergency UN Security Council meeting is expected to take place early tomorrow morning (NZT).
"New Zealand will work with other Security Council members to make sure there is a strong response to this latest provocation," Mr Lotu-Iiga said.
• South Korea, China, and Japan to hold emergency meetings.
• Experts cast doubt over the weapon used.
• Fourth nuclear test in North Korea since 2006.
• Shinzo Abe condemns test.
CNN reports that Pyongyang says they are defending themselves against the United States and demanding North Korean sovereignty be respected.
The news reader who made the announcement on state television said "the republic's first hydrogen bomb test has been successfully performed at 10:00 am on January 6, 2016, based on the strategic determination of the Workers' Party."
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.
Experts say that ballistic missiles and rockets in satellite launches share similar bodies, engines and other technology. The U.N. called the 2012 launch a banned test of ballistic missile technology.
Some analysts say the North hasn't likely achieved the technology needed to manufacture a miniaturized warhead that could fit on a long-range missile capable of hitting the U.S. But there is a growing debate on just how far the North has advanced in its secretive nuclear and missile programs.
This tweet shows the waveforms for the test as compared to the previous in 2013.
Overlay of seismic waveforms for station MDJ for North Korean tests suggests similar size to 2013 via @drrocks1982 pic.twitter.com/6zBDci1Och
— Jascha Polet (@CPPGeophysics) January 6, 2016
#NorthKorea joins the h-bomb club with #US #Russia #China #France #Britain pic.twitter.com/Blq14MTn0s
— Zaid Benjamin (@zaidbenjamin) January 6, 2016
South Korean and Japanese officials have hastily convened emergency meetings.
Japanese Prime Minister Shinzo Abe says the North Korean announcement of a hydrogen bomb test is a threat to his nation's safety.
Abe told reporters: "We absolutely cannot allow this, and condemn it strongly."
He called it a violation of the U.N. Security Council agreements that is against the global efforts toward nuclear disarmament.
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.
South Korean officials detected an "artificial earthquake" near North Korea's main nuclear test site today, a strong indication that nuclear-armed Pyongyang had conducted its fourth atomic test.
The US Geological Survey rated the magnitude of the seismic activity at 5.1 on its website.
An official from the Korea Meteorological Administration, South Korea's weather agency, said it believed the earthquake was caused artificially based on their analysis of the seismic waves and that it originated 49km (30 miles) north of Kilju, the northeastern area where North Korea's main nuclear test site is located.
Coreia do Norte realiza um teste(bem sucedido)de uma bomba de hidrogênio: https://t.co/PrYaxkgx9W pic.twitter.com/4rXTMyMZNN
— Brener Pereira (@BrenerTP) January 6, 2016
The country conducted all three previous atomic detonations there.
South Korean government officials couldn't immediately confirm whether a nuclear blast or natural earthquake had taken place.
North Korea conducted its third nuclear test in February 2013.
Another test would further North Korea's international isolation by prompting a push for new, tougher sanctions at the United Nations and worsening Pyongyang's already bad ties with Washington and its neighbours. Pyongyang is thought to have a handful of crude nuclear weapons.
The United States and its allies worry about North Korean nuclear tests because each new blast brings the country closer to perfecting its nuclear arsenal.
Since the elevation of young leader Kim Jong Un in 2011, North Korea has ramped up angry rhetoric against the leaders of allies Washington and Seoul and the US-South Korean annual military drills it considers invasion preparation.
