North Korea on Sunday announced that it has successfully conducted a test of a hydrogen bomb that is meant to be loaded into an intercontinental ballistic missile.
The news reader of the North Korean Central Television announcer said North Korea's leader Kim Jong Un ordered the test, hours after Seoul and Tokyo detected unusual seismic activity at North Korea's nuclear test site.
Seismological data from the United States Geological Survey (USGS) showed that an explosion caused a 6.3-magnitude tremor in the country's northeast, not far from the country's Punggye-ri nuclear test site.
North Korea has conducted a sixth nuclear test, the Japanese government said, a move the United States and its allies in the region are likely to view as a major provocation.
South Korea and Japan are gathering and analyzing data to confirm details of the test, which Japanese Minister Shinzo Abe said could not be tolerated, CNN reported.
"If North Korea did indeed conduct a nuclear test, we absolutely cannot tolerate and must protest firmly. We will convene a National Security council meeting to gather and analyze the information," Abe said in a live television broadcast prior to Kono's announcement.
The quake was felt in northern China, with emergency sirens blaring in Yanji, near the North Korean border, according to local media.
As per the China's Earthquake Administration, North Korea has carried out its sixth nuclear test.
The administration had earlier detected a quake in North Korea, of 5.2 magnitude.
Eight minutes after the first quake, the administration reported about another quake occurred in North Korea of magnitude 4.6, which has been described as a 'collapse'.
Meanwhile, Japan has dispatched so-called "radiation sniffer" planes to take samples to confirm that a nuclear explosion did in fact take place.