Experts analysing footage released by North Korea last week showing the firing of a submarine-launched ballistic missile say the images appear to be faked.
In defiance of a United Nations ban, North Korea said it tested ballistic missile technology that would allow it to launch a nuclear warhead from a submarine.
North Korea released the submarine launch footage after it separately conducted a fourth nuclear weapons test on January 6.
Two days later, North Korean state television aired footage of the submarine test which it said took place in December.
Unlike a previous submarine-launched ballistic missile (SLBM) test in May, it was not announced at the time.
At the weekend, South Korea’s military said North Korea appeared to have modified the video and edited it with Scud missile footage from 2014.
However, an official said the ejection technology might have improved since that test.
Now, analysis by the California-based James Martin Centre for Nonproliferation Studies (CNS) shows two frames of the state media video where flames engulf the missile and small parts of its body break away.
“The rocket ejected, began to light, and then failed catastrophically,” CNS senior research associate Melissa Hanham said.
“North Korea used heavy video editing to cover over this fact.”
Ms Hanham said North Korea state media used different camera angles and editing to make it appear the launch was several continuous launches, when in fact it was a single event.