The announcement — which has not been verified — followed detection of a 5.1 magnitude earthquake near North Korea’s known nuclear test site.
Government of the North Korea said it successfully tested a miniaturized hydrogen nuclear device on Wednesday, claiming a significant advance in the isolated state’s strike capability and setting off alarm bells in Japan and South Korea.
The test, the fourth time North Korea has exploded a nuclear device, was ordered by young leader Kim Jong Un, state media said.
“Let the world look up to the strong, self-reliant nuclear-armed state,” Kim wrote in what North Korean state TV displayed as a handwritten note.
The announcement on North Korean State TV followed detection of a 5.1 magnitude earthquake near its known nuclear test site earlier. The state claims the test was done in “self defense against the U.S. having numerous and humongous nuclear weapons.”
The reported nuclear test drew condemnation abroad, including from China and Russia, North Korea’s two main allies. China expressed “resolute opposition” and said it would lodge a protest with Pyongyang.
The White House, while it could not yet verify the success of the nuclear test, quickly condemned Pyongyang’s violation of international law and promised to defend its South Korean ally.
“We have consistently made clear that we will not accept it as a nuclear state,” a White House spokesperson said in a statement.
Experts Skeptical: Was It Really An H-Bomb?
Last month, Kim appeared to claim his country had developed a hydrogen bomb, also known as a thermonuclear device, a step up from the less powerful atomic bomb, but the United States and outside experts were skeptical at the time.
Some analysts questioned whether Wednesday’s test was indeed of a hydrogen device.
“North Korea has made claims about its nuclear and missile programs in the past that simply have not held up to investigation,” said Melissa Hanham, a senior research associate at the California-based James Martin Center for Nonproliferation Studies.
The device had a yield of about 6 kilotons, according to the office of a South Korean lawmaker on the parliamentary intelligence committee – roughly the same size as the North’s last test, which was equivalent to 6-7 kilotons of TNT.
“Given the scale, it is hard to believe this is a real hydrogen bomb.
“They could have tested some middle stage kind (of device) between an A-bomb and H-bomb, but unless they come up with any clear evidence, it is difficult to trust their claim,” said Yang Uk, a senior research fellow at the Korea Defence and Security Forum.
Miniaturising, which would allow the device to be adapted as a weapon and placed on a missile, would pose a new threat to the United States and its regional allies, Japan and South Korea.
South Korea’s defense ministry said a small amount of hydrogen may have been added to a device North Korea tested, media reported.
However, no radiation had been detected from North Korea’s nuclear test at Japanese monitoring posts, Japan’s top government spokesman said.
“As of 4.45 this afternoon, no radiation has been detected at any Japanese monitoring posts,” chief cabinet secretary Yoshihide Suga told a news conference.
International Response: UN To Hold Emergency Meeting
The United Nations Security Council is planning to meet on Wednesday morning, council diplomats said. Speaking to Reuters on condition of anonymity late on Tuesday, one diplomat said the meeting would likely be held behind closed doors.
It was not immediately clear what action, if any, the 15-nation council was planning to take.
South Korea’s defense ministry said that the country’s armed forces are stepping up their monitoring of North Korea and would take all possible measures, including possible United Nations sanctions, to ensure Pyongyang pays the price after its fourth nuclear test.
“Our government strongly condemns North Korea ignoring repeated warnings from us and the international community and pushing ahead with the fourth nuclear test, which clearly violated the U.N. resolutions,” Cho Tae-yong, a senior security official at the South Korean presidential office said.
Separately, South Korea’s Yonhap News agency said President Park Geun-hye will preside over a national security council meeting at 0430 GMT.
Meanwhile, Japanese Prime Minister Shinzo Abe said the nation would make a firm response to North Korea’s challenge against nuclear non-proliferation, calling its latest nuclear test a threat to Japan’s security.
Abe, speaking to reporters, said Japan absolutely could not tolerate North Korea’s nuclear testing.
“A nuclear test by North Korea poses a major threat to our national security. It cannot be acceptable. We strongly denounce it,” Abe said.
Although China, arguably North Korea’s closest ally, has not officially weighed in, its state news agency did.
Xinhua disapproved of North Korea’s actions, saying the latest test ran counter to the goal of runs counter to the goal of denuclearisation. It warned that any practice that disrupts stability in northeast Asia is “undesirable and unwise.”
In Australia, prime minister of foreign affairs Julie Bishop followed suit in denouncing its northern aggressor, even calling it a “rogue state” that threatens peace in the region.
“Today’s nuclear test confirms North Korea’s status as a rogue state and a continuing threat to international peace and security,” Bishop said in a statement.
She also called for stronger sanctions and for the UN Security Council to take appropriate actions.
Back in the U.S., presidential hopeful Marco Rubio called Kim Jung-un a “lunatic” and blamed the Obama administration’s for the leader’s increased abilities.
“North Korea is run by a lunatic who has been expanding his nuclear arsenal while President Obama has stood idly by,” the Republican senator from Florida blasted. “If this test is confirmed, it will be just the latest example of the failed Obama-Clinton foreign policy.”