To the dismay of most countries around the world, North Korea says it has successfully tested a nuclear weapon that could be loaded on to a long-range missile.The country said its sixth nuclear test was a perfect success. This was especially scary since hours earlier seismologists had detected an earth tremor.Pyongyang said it had tested a hydrogen bomb which is many times more powerful than an atomic bomb.According to analysts this might not be true, yet it is a source for concern. South Korean officials said the latest test took place in Kilju County, where the North's Punggye-ri nuclear test site is situated.