North Korea says it tested a hydrogen bomb, calls it a "complete success"

North Korea says it has successfully conducted a test of a hydrogen bomb meant for an intercontinental ballistic missile. The confirmation announcement was made on state television.

Pyongyang appeared to carry out a sixth nuclear test on Sunday, with seismic monitors measuring an "explosion" of 6.3 magnitude near its main test site, sending tensions over its weapons ambitions to new heights.

The apparent test came just hours after it claimed to have developed a hydrogen bomb that could be loaded into the country's new intercontinental ballistic missile.

South Korea's Joint Chiefs of Staff said in a statement that the seismic tremor was detected near the North's Punggye-ri test site.

United States Geological Survey recorded the magnitude at 6.3 – larger than any previous test.

Jana Pursely, a USGS geophysicist, told AFP: "It's an explosion rather than an earthquake."

Nuclear-armed Pyongyang has long sought the means to deliver an atomic warhead to the United States, its sworn enemy.

Sixth nuclear test

Japanese Prime Minister Shinzo Abe said a sixth nuclear test by Pyongyang would be "absolutely unacceptable," after a 6.3 magnitude explosion in the North indicated a new detonation.

"If it forcibly conducted a nuclear test, it's absolutely unacceptable. We have to strongly protest it," Abe said.  

Abe on Sunday spoke with US President Donald Trump by phone and said that in face of an "escalating" situation with North Korea, close cooperation between their countries and South Korea was needed.

Abe and Trump also agreed that pressure on North Korea must be raised, Abe told reporters after the conversation.

North Korea last year conducted its fourth and fifth nuclear tests, saying the fourth in January 2016 was a successful hydrogen bomb test, although outside experts questioned whether it was a full-fledged hydrogen bomb.

The fifth nuclear test in September 2016 was measured to be possibly North Korea’s biggest detonation ever, but the earthquake it caused was still not believed to be big enough to demonstrate a thermonuclear test.

Heightened tension

The sixth test comes amid heightened regional tension following Pyongyang’s test launch of two ICBM-class missiles in July that potentially had a range of about 10,000 km that could hit many parts of the mainland US.

North Korea has recently threatened to land missiles near the US Pacific territory of Guam.

The hydrogen bomb’s power is adjustable to hundreds of kilotons and can be detonated at high altitudes. Its indigenously produced components will allow the country to build as many nuclear weapons as it wants, KCNA, the North's news agency, said.

North Korean leader Kim Jong-un visited the country’s Nuclear Weapons Institute and “watched an H-bomb to be loaded into new ICBM,” KCNA said.

“All components of the H-bomb were homemade and all the processes ... were put on the Juche basis, thus enabling the country to produce powerful nuclear weapons as many as it wants, he said.”

Under Kim Jong-un, North Korea has pursued work on building nuclear weapons and long-range ballistic missiles that can deliver them at an unprecedented pace, defying UN sanctions and international pressure.