North Korea claims successful test of nuclear warhead

North Korea says it has successfully tested a nuclear warhead that can be mounted on ballistic rockets, after potentially the most powerful nuclear test of five the country has conducted since 2006.

State media said the test showed that North Korea had a standardized nuclear warhead that would enable North Korea to “produce at will and as many as it wants a variety of smaller, lighter and diversified nuclear warheads of higher strike power.”

South Korea condemned the test, saying it was a clear violation of the United Nations Security Council resolution. 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.

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, from South Korea’s Meteorological Administration.

By comparison, the nuclear bomb dropped on Hiroshima was 15 kilotons.

“We are currently analyzing whether it was a successful test,” a South Korean 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.

Sniffer planes

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 which was designed to hide activity to the site, analysts said.

In January, North Korea claimed it had successfully tested a hydrogen bomb, a move that was condemned by the UN Security Council and led to punitive sanctions on the North Korean regime.

‘Absolutely unacceptable’

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, said CNN Seoul correspondent Paula Hancocks.

In addition to January’s nuclear test, North Korea in March claimed to have miniaturized nuclear warheads and has tested several ballistic missiles, including some launched from a submarine.

Sanctions, including ones targeting Kim Jong Un 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 U.S. President Barack Obama left Asia after attending international summits in China and Laos.

Earlier, the U.S. Geological Survey reported a 5.3 magnitude earthquake in North Korea, but later termed it an explosion. The South Korea Meteorological Administration measured the quake as magnitude 5.0 but said it believed it was artificial.