N Korea's 6th nuke test 9.8 times powerful than 5th: S Korea
The hydrogen bomb tested by North Korea on Sunday, marking its sixth nuclear test, was 9.8 times more powerful than the reclusive state's fifth nuclear test conducted in September 2016, South Korean state weather agency has claimed. North Korea has hailed the bomb test as a "perfect success" and said it is a "meaningful" step to complete its nuclear programme.n