North Korea conducted a fifth nuclear test Friday, potentially its most powerful yet, South Korean officials said.
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.
South Korea condemned the test and said it was a clear violation of the United Nations Security Council resolution.
“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,” South Korean President Park Geun-hye said in a statement.
The blast had the explosive power of 10 kilotons, almost twice as large as the previous test, said Kim Nam-wook, a 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 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 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.
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.
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.