[Breaking news update, posted at 22:39 p.m. ET]
South Korea now believes North Korea conducted a nuclear test, an official with the South Korean Defense Ministry tells CNN. “We are currently analyzing whether it was a successful test,” the official said.
[Previous story, posted at 22:01 p.m. ET]
South Korea’s military says it is analyzing whether North Korea has conducted its fifth nuclear test after seismic activity was reported Friday morning.
A magnitude 5.3 earthquake was detected at 9.30 a.m. local time near Punggye-ri, Kilju County — the same location as four other tests, the most recent of which was in January.
South Korea’s Prime Minister Hwang Kyo-ahn convened an emergency National Security Council.
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.
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.
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.
USGS said the seismic activity hit 18 kilometers east north east of Sungjibaeham, North Korea, with a depth of 0 kilometers.