Kim Jong-Un
North Korean leader Kim Jong Un tours the Sci-Tech Complex in Pyongyang, North Korea. Reuters

Footage of a ballistic missile apparently being successfully launched from a submarine was faked by North Korea, according to an analysis by a California think tank.

The video was released just two days after Pyongyang claimed it had conducted its fourth nuclear test, this time of a hydrogen bomb.

The "launch" test apparently demonstrated in the footage was critical because it could have indicated that the rogue nation was capable of delivering a nuclear bomb long distances with a missile.

But 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 Centre for Nonproliferation Studies (CNS).

The CNS analysis discovered two frames of video from state media where flames engulf the missile and small parts of its body break away. But North Korea "used heavy video editing to cover over this fact," Hanham said in an email.

They used rudimentary editing techniques to crop and flip old video footage of an earlier test and Scud missile launch to make it appear to be a successful launch, the video analysis showed, Reuters reported.

Pyongyang's claim that it tested a hydrogen bomb on 6 January has also been met with skepticism by experts, though investigations are continuing.