NEW satellite images of North Korea bases appear to show the power hungry state gearing up for a game-changing nuclear missile test - this time from a submarine.

It comes as a North Korean subs have been reportedly spotted by US spy agencies in international waters engaging in "unusual activity".

5 Experts believe changes at the base betray an impending operation Credit: Getty Images

5 The North Koreans appear to be investing in its submarine forces Credit: Getty Images

5

The satellite pictures show a SINPO-class submarine, which is designed to launch ballistic missiles, in the Sinpo South shipyard in the east of the secretive state.

But North Korean watchers 38North, which monitors military activity in the Stalinist country, has spotted changes on the boat and the facility it is docked in.

The analysts believe satellite images indicate preparations for a major operation.

Its report states: “While the precise reason for this movement is unclear, one possibility is that it may have been long-term preparations for the recently reported voyage or an upcoming missile test.”

Other images show huge development at the shipyard.

Long-range ballistic missiles (ISBMs), and their submarine-housed counterparts (SLBMs), are rockets which can carry nuclear bombs and would be capable of striking the west coast of the US including cities such as Los Angeles and Seattle.

5 Kim Jong-un has been repeatedly threatening to nuke America and it's feared his next launches will be seaborne Credit: Reuters

Officials today told CNN that North Korea is developing its submarine based missile capability.

Researchers believe the threat posed by Kim Jong-un has been underestimated – with the latest missile test soaring seven times higher than the International Space Station.

North Korea announced the completion of its first ever successful intercontinental ballistic missile launch earlier this month.

The ICBM was the first of its kind to be launched by the secret state and the test sent shockwaves across the world after the trigger-happy tyrant vowed to turn the US into a “pile of ash”.

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5 The image also show major expansion at the shipyard Credit: Getty Images

A successful ICBM test launch marks a significant step forward for secretive Pyongyang's weapons capability.

ICBMs have a minimum range of about 3,418 miles, but some are designed to travel 6,214 miles or further.

California is roughly 5,592 miles from North Korea.

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