South Koreans watch TV news showing North Korea's breaking news, at Seoul station, in Seoul, South Korea. Picture: EPA/JEON HEON-KYUN
South Koreans watch TV news showing North Korea's breaking news, at Seoul station, in Seoul, South Korea. Picture: EPA/JEON HEON-KYUN

SEOUL — Footage of a North Korean submarine-launched ballistic missile (SLBM) test released by Pyongyang two days after it announced it had conducted the country’s fourth nuclear test last week, was faked, according to an analysis by a California-based think tank.

In defiance of a United Nations (UN) ban, the isolated country has said it has ballistic missile technology that would allow it to launch a nuclear warhead from a submarine, although experts and analysis of North Korean state media cast doubt on the claim.

North Korea said on Tuesday its nuclear test was not intended to be a provocation or threat, as it laid out plans for a weapons system capable of obliterating the entire US.

A lengthy commentary by the official KCNA news agency underlined North Korea’s claim that last Wednesday’s test was of a powerful, miniaturised hydrogen bomb, which marked a "new high stage" in the country’s search for a credible nuclear deterrent.

The KCNA commentary said the test was an indispensable stage of the "normal course" other countries have taken to the development of a two-stage fission-fusion H-bomb.

"The test was neither to ‘threaten’ anyone, nor to ‘provoke’ someone for a certain purpose," KCNA said, insisting that the main focus was on providing a "sure guarantee" of North Korea’s immunity from attack by hostile forces.

Prime among those forces was the US, it said, offering an apocalyptic vision of how it would respond to US aggression.

North Korean scientists and technicians "are in high spirit to detonate H-bombs of hundreds of kilotons and megatons, capable of wiping out the whole territory of the US all at once," it said.

Outside experts say the yield from Wednesday’s test was about six kilotons, while an H-bomb would have been at least 100 times more powerful.

North Korean state television aired footage on Friday of the latest test, said to have taken place in December. Unlike a previous SLBM test in May, it had not been announced at the time.

"The rocket ejected, began to light, and then failed catastrophically," said Melissa Hanham, a senior research associate at the California-based Middlebury Institute’s James Martin Center for Nonproliferation Studies (CNS).

South Korea’s military said on Saturday that North Korea appeared to have modified the video and edited it with Scud missile footage from 2014 although an official told Reuters that the ejection technology might have improved since the May test.

The CNS analysis shows two frames of video from state media where flames engulf the missile and small parts of its body break away.

"North Korea used heavy video editing to cover over this fact," Ms Hanham said in an e-mail. "They used different camera angles and editing to make it appear that the launch was several continuous launches, but played side by side you can see that it is the same event."

North Korean propagandists used rudimentary editing techniques to crop and flip old video footage of a more successful ejection test from May and a Scud missile launch from June last year, the video analysis showed.

The North’s claim that its fourth and most recent nuclear test, conducted last Wednesday, was of a more advanced and powerful hydrogen bomb has drawn scepticism from the US government and experts.

It is also unclear if North Korea has developed a nuclear device small enough to mount on a missile.

Reuters and AFP