N Korea says it conducts successful powerful H-bomb test

North Korea said today it has conducted a powerful hydrogen bomb test, a defiant and surprising move that, if confirmed, would be a huge jump in Pyongyang's quest to improve its still-limited nuclear arsenal.
A television anchor said in a typically propaganda-heavy statement that the North had tested a "miniaturized" hydrogen bomb, elevating the country's "nuclear might to the next level" and providing it with a weapon to defend against the United States and its other enemies.
The statement said the test was a "perfect success," and the announcement was celebrated on the streets of Pyongyang. South Korean President Park Geun-hye ordered her military to bolster its combined defense posture with US forces and called the test a "grave provocation" and "an act that threatens our lives and future."

There has long been skepticism by Washington and nuclear experts about past North Korean claims about H-bombs, which are much more powerful, and much more difficult to make, than atomic bombs.
A confirmed test, however, would be seen as extremely worrying and lead to a strong push for new, tougher sanctions on North Korea at the United Nations, which quickly announced an emergency Security Council meeting on North Korea. It would also further worsen already abysmal relations between Pyongyang and its neighbors.
North Korean nuclear tests catch global attention because each new blast is seen as pushing North Korea's scientists and engineers closer to their goal of building a bomb small enough to place on a missile that can reach the US mainland.

A successful H-bomb test would be a big step for the North, and the announcement prompted skepticism. Fusion is the main principle behind the hydrogen bomb, which can be hundreds of times more powerful than atomic weapons that use fission.

In a hydrogen bomb, radiation from a nuclear fission explosion sets off a fusion reaction responsible for a powerful blast and radioactivity.
Writing in December, after North Korean leader Kim Jong Un bragged of H-bomb capabilities, nuclear expert Jeffrey Lewis noted that building such a bomb "would seem to be a bit of a stretch for the North Koreans."
But, he wrote on the North Korea-focused 38 North website, "The North has now had a nuclear weapons program for more than 20 years. This program has yielded three nuclear tests. North Korean nuclear scientists have access to their counterparts in Pakistan, possibly Iran and maybe a few other places. We should not expect that they will test the same fission device over and over again.