美国有线新闻 CNN 朝鲜宣布成功进行氢弹试验 威力远大于前

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Once again, North Korea has defied international demands to give up its nuclear and missile programs. They're illegal, as far as the United Nations is concerned. They're a right as far as North Korea is concerned.

And the communist country said on Sunday that it had successfully tested out a hydrogen bomb, an extremely dangerous nuclear weapon. It was apparently¹ tested underground, causing an earthquake of magnitude 6.3, a strong tremor².

And North Korea looks like it's getting ready to launch more test missiles, according to South Korea. That country has strengthened an American made missile defense³ system. It says the U.S. is going to increase its military presence in the region.

This would be the sixth time that North Korea has tested a nuclear weapon. But it appears to be the first time it's tested one this powerful.

SUBTITLE⁴: North Korea and the H-Bomb.

PAULA HANCOCKS, CNN INTERNATIONAL CORRESPONDENT: Hydrogen bombs have never been used before in warfare⁵. Atomic bombs have. This is what the U.S. struck on Nagasaki and Hiroshima back in 1945, ultimately killing⁶ more than 200,000 people. But the H-bomb is at least 100 times more powerful than the A-bomb. The H-bomb has a far larger yield than traditional weapons, meaning that devices can be smaller, while causing greater devastation⁷.

Atomic bombs used a process called fission⁸ to split plutonium or uranium into smaller atoms and a chain reaction releasing massive amounts of energy. Hydrogen bombs used fusion⁹, instead of splitting the atoms, it combines small atoms like hydrogen. Essentially¹⁰, it's two bombs in one.

North Korea first claimed back in January 2016 it had successfully tested a hydrogen bomb. If it does in fact have this capability¹¹ today, it has joined a very select club. Only the U.S., Russia, the U.K., France, and China have carried out confirmed tests of hydrogen bombs.