North Korea confirms sixth nuclear test

The official Korean Central News Agency (KCNA) said the hydrogen bomb test on Sunday morning, ordered by leader Kim Jong-un, was a "perfect success".

The test took place at 12pm (03:30 GMT) and was carried out to "examine and confirm the accuracy and credibility" of North Korea's technology, KCNA said.

The test was of a bomb with "unprecedently large power" and "marked a very significant occasion in attaining the final goal of completing the state nuclear force", KCNA said.

Pyongyang earlier on Sunday reported details of its latest weapon, claiming it has developed a more advanced nuclear bomb that can be loaded onto a intercontinental ballistic missile (ICBM).

KCNA released undated photographs of Kim inspecting the weapon.

KCNA said the hydrogen bomb's power is adjustable to hundreds of kilotons and can be detonated at high altitudes, with its indigenously produced components allowing the country to build as many nuclear weapons as it wants.

The latest test took place in breach of UN sanctions and is certain to further increase tensions between Pyongyang and the United States and its allies.

There was no independent confirmation that the detonation was a hydrogen bomb.

It was Pyongyang's first nuclear test since US President Donald Trump took office, and marked a direct challenge to Trump, who hours earlier had talked by phone with Japanese Prime Minister Shinzo Abe about the "escalating" nuclear crisis in the region.

Japan was the first country to confirm the North Korean nuclear test, while South Korea described the "artificial quake" as "the most powerful" test yet.

Al Jazeera's Scott Heidler, reporting from Tokyo, said Japanese officials have already concluded a national security emergency meeting and have registered a protest with the North Korean embassy in Beijing.

"Out of today's meeting, [Japanese officials] called the test 'a new threat'," said Heidler. "They said they want to work with the United States and South Korea in convening a UN Security Council meeting, where they would like to pursue a new sanctions resolution."

The US Geological Survey was first to report an earthquake in North Korea on Sunday, citing a first tremor of 6.3 magnitude with a depth of 23 kilometres.

China later said it had also detected a second quake in North Korea of magnitude 4.6, which came eight minutes after the initial tremor.

Ross Feingold, a Taiwan-based Asia political analyst, told Al Jazeera that the development North Korean weapons has been advancing steadily.

"There has clearly been a pace of technological improvement over a period of time, whether it is with nuclear bombs themselves or with the missile delivery technlogy," he said. "One thing we know from the North Koreans is that they probabaly have better technological capabilty than a lot of the analysts had given them credit for in the past. And more significantly, they do learn from mistakes."

Source: Al Jazeera and news agencies