NK's most powerful nuclear test a 'perfect success,' says leader Kim

North Korea conducted its sixth and most powerful nuclear test yesterday, which it said was an advanced hydrogen bomb for a long-range missile. The test marked a dramatic escalation of the regime’s stand-off with the United States and its allies.

North Korea, which carries out its nuclear and missile programs in defiance of United Nations Security Council resolutions and sanctions, said on state television that a hydrogen bomb test ordered by leader Kim Jong Un had been a “perfect success.”

The bomb was designed to be mounted on its newly developed intercontinental ballistic missile (ICBM), North Korea said.

The test registered with international seismic agencies as a manmade earthquake near a test site in North Korea. Japanese and South Korean officials said it was around 10 times more powerful than the tremor picked up after North Korea’s last nuclear test a year ago.

Experts who studied the impact of the earthquake caused by the explosion — measured by the US Geological Survey at 6.3 magnitude — said that there was enough strong evidence to suggest North Korea has either developed a hydrogen bomb or was getting very close.

Under third-generation leader Kim, North Korea has been pursuing a nuclear device small and light enough to fit on a long-range ballistic missile, without affecting its range and making it capable of surviving re-entry.

North Korea claimed in January last year to have tested a miniaturized hydrogen bomb, also known as a thermonuclear device, but outside experts were skeptical, suggesting it could have been a “boosted device,” an atomic bomb that uses some hydrogen isotopes to increase its explosive yield.

The test comes amid heightened regional tension following Pyongyang’s two tests of ICBMs in July that potentially could fly about 10,000 kilometers, putting many parts of the US mainland within range.

One expert said the size of yesterday’s detonation meant it was possible it could be a hydrogen bomb test.

“The power is 10 or 20 times or even more than previous ones,” said Kune Y Suh, a nuclear engineering professor at Seoul National University. “That scale is to the level where anyone can say (it was) a hydrogen bomb test.”

When the test took place, people in the Chinese city of Yanji, on the border with North Korea, said they felt a tremor that lasted roughly 10 seconds, followed by an aftershock.

“I was eating brunch just over the border here in Yanji when we felt the whole building shake,” said Michael Spavor, director of the Paektu Cultural Exchange, which promotes business and cultural ties with North Korea.

“It lasted for about five seconds. The city air raid sirens started going off.”

Earthquakes that have been triggered by North Korean nuclear tests have gradually increased in magnitude since Pyongyang’s first test in 2006, indicating that the country is steadily increasing the destructive power of its nuclear technology.

The Comprehensive Test Ban Treaty Organization in Vienna said it detected an “unusual seismic event” in North Korea that was larger than previous nuclear tests.

Hours before the test, North Korea’s state news agency KCNA released pictures showing leader Kim inspecting a silver, hourglass-shaped warhead during a visit to the country’s nuclear weapons institute, accompanied by scientists.

Kim “watched an H-bomb to be loaded into new ICBM” and “set forth tasks to be fulfilled in the research into nukes,” the agency said.

The shape shows a marked difference from pictures of the ball-shaped device North Korea released in March last year, and appears to indicate the appearance of a two-stage thermonuclear weapon, said Lee Choon-geun, senior research fellow at South Korea’s state-run Science and Technology Policy Institute.

KCNA said North Korea “recently succeeded” in making a more advanced hydrogen bomb. 

“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,” KCNA quoted Kim as saying.

Juche is North Korea’s homegrown ideology of self-reliance that is a mix of Marxism and extreme nationalism preached by state founder Kim Il Sung, the current leader’s grandfather. It says its weapons programs are needed to counter US aggression.