Japanese Prime Minister Shinzo Abe said a sixth nuclear test by Pyongyang would be "absolutely unacceptable," after a 6.3 magnitude explosion in the North indicated a new detonation.

"If it forcibly conducted a nuclear test, it's absolutely unacceptable. We have to strongly protest it," Abe said.  

"There is a possibility that this is not a natural quake and that North Korea conducted a nuclear test," he said, adding that the Japanese weather agency detected a seismic wave.

source: AFP