North Korea said Tuesday that it had conducted a new, more powerful underground nuclear test using more sophisticated technology to protect its national security against the US’s hostile policy.

South Korea’s TV “Channel One” on Tuesday quoted the country’s Defense Ministry believing that the Democratic People's Republic of Korea has conducted a nuclear test. The report came shortly after a 5.1-magnitude earthquake was detected in the DPRK, a potential sign that the country has finally undertaken its third nuclear test. The South Korean Defense Ministry estimated the nuclear test at 6 to 7 kilotons, while an earlier report from the Yonhap News Agency said the ministry calculated the explosion at 10 kilotons. According to Yonhap, the earthquake was detected at 11:57 local time in the DPRK's Kilju County, North Hamkyung Province, where a nuclear test site is located.

Meanwhile, Japanese government spokesman Yoshihide Suga affirmed the possibility that Pyongyang conducted a nuclear test. He said Japanese Prime Minister Shinzo Abe asked related agencies to gather information about the tremor and organize an urgent security meeting. On Tuesday, Japanese Prime Minister Shinzo Abe said Japan would take into consideration of sanctions against Pyongyang.

The world community is now concerned about the nature and scale of the nuclear test to see the development of Pyongyang’s nuclear technology.

Earlier, the DPRK vowed to proceed with missile and nuclear tests targeting the US after the UN Security Council adopted a resolution to condemn its December 12 rocket launch.