NewsWorldAsia North Korea nuclear test: What is a hydrogen bomb? Is it the same as a thermonuclear device? Who else has nuclear weapons?

Experts say there is enough evidence to suggest reclusive state has either developed hydrogen bomb or is getting very close

North Korea said it had conducted its sixth and most powerful nuclear test, drawing swift international condemnation.

The North said it had detonated an advanced hydrogen bomb, marking a major step in its long-stated goal of developing a nuclear-tipped missile capable of hitting a major US city.

Experts who studied the impact of the earthquake caused by the explosion, measured by the US Geological Survey at magnitude 6.3, said there was enough strong evidence to suggest the reclusive state has either developed a hydrogen bomb or was getting very close.