By Katie Hunt and KJ Kwon, CNN
North Korea said it has hit the button on its fifth and potentially most powerful nuclear test Friday morning, claiming to have successfully tested a nuclear warhead.
State media said the warhead could be mounted on ballistic rockets and would enable North Korea to produce “a variety of smaller, lighter and diversified nuclear warheads of higher strike power.”
“It’s hard for us to verify their claim. My deep fear is that they will launch a live nuclear weapon on one of their missiles, but that would be extremely dangerous as that could trigger a war,” said Melissa Hanham, a senior research associate at the James Martin Center for Nonproliferation Studies.
South Korea, Japan and China condemned the test, saying it was a clear violation of the UN Security Council resolution.
South Korean President Park Geun-hye called Kim Jong Un’s regime “fanatically reckless.”
“The only thing that Kim Jong Un regime can gain from the nuclear tests is stronger sanctions from the international community and its isolation. Such provocation will eventually hasten its path to self-destruction,” she said in a statement.
National security adviser Susan Rice briefed President Barack Obama about the situation, White House press secretary Josh Earnest told pool reporters aboard Air Force One on the US leader’s return trip from Asia. Earnest said the President spoke separately to South Korean and Japanese leaders by phone, reassuring them of “the unbreakable US commitment to the security of our allies in Asia and around the world.”
Seismic activity, with a magnitude of 5.3, was detected around 9 a.m. local time (8:30 p.m. ET) near Punggye-ri, Kilju County — the same location as four other tests, the most recent of which was in January.
The blast had the explosive power of 10 kilotons, almost twice as large as the previous test, said Kim Nam-wook of South Korea’s Meteorological Administration.
By comparison, the nuclear bomb that the United States dropped on Hiroshima in World War II was 15 kilotons.
“We are currently analyzing whether it was a successful test,” a South Korean National Defense Ministry official told CNN.
A US official told CNN that it looked like a nuclear test but confirmation would be dependent on seismic readings, location of the seismic event and whether it can be matched to an underground test site.
The US Air Force is expected to start flying the WC-135 Constant Phoenix Aircraft in the coming hours to take air samples and see if it can determine a nuclear event occurred. Japan has sent four jets to test for radiation.
Satellite images had shown new activity at the Punggye-ri nuclear test site in recent weeks, according to North Korea monitoring site 38North.
A small number of mining carts could be seen as well as a new canopy designed to hide activity to the site, analysts said.
In January, North Korea claimed it had successfully tested a hydrogen bomb, a move the Security Council condemned and that led to punitive sanctions on the North Korean regime.
Japanese Prime Minister Shinzo Abe told reporters Friday that if North Korea had conducted another nuclear test it was “absolutely unacceptable.”
“We must lodge a strong protest,” he said.
Concern has been growing that North Korea is testing weapons at an unprecedented pace this year, CNN international correspondent Paula Hancocks said.
In addition to January’s nuclear test, North Korea in March claimed to have miniaturized nuclear warheads and tested several ballistic missiles, including some launched from a submarine.
Sanctions, including ones targeting the North Korean leader personally, have had little effect.
Philip Yun, executive director of Ploughshares Fund, a group that advocates nuclear disarmament, said that North Korea had become “increasingly aggressive.”
“The reason is because the international community is not taking it seriously. There’s no prospect right now for any talks or negotiations. This will only escalate the situation,” he said.
Friday is North Korea’s national day, and the nuclear test also comes just after the US President left Asia following international summits in China and Laos.
Earlier, the US Geological Survey reported a 5.3-magnitude earthquake in North Korea but later termed it an explosion. South Korea’s Meteorological Administration measured the quake as magnitude 5.0 but said it believed it was artificial.