Satellite images indicate that North Korea is starting work on a submarine that will be larger than anything it can presently deploy, with analysts suggesting the vessel may be used as the platform for Pyongyang's newly developed submarine-launched ballistic missiles.

Images captured by commercial satellites in September show components compatible with the construction of a submarine stockpiled at the Sinpo South Shipyard, according to the 38 North web site, operated by the US-Korea Institute at Johns Hopkins University.

"While there is no direct evidence that the program is for a boat to carry the ballistic missile currently under development, the presence of an approximately 10-metre in diameter [32 feet] circular component outside the facility’s recently renovated fabrication hall may be intended as a construction-jig or as a component for the pressure hull of a new submarine," the report claims.