North Korean leader Kim Jong Un (front) stands on the conning tower of a submarine. (Reuters)
A website that monitors North Korea says the isolated nation may be exploring how to launch ballistic missiles from submarines or ships.
The North would still be years away from deploying such missiles, but the finding adds to concern over its weapons development.
An analysis published on Tuesday by the website 38 North cites recent satellite imagery showing a 12-meter (39-foot)- tall structure on a concrete base that might be used for testing how a missile would eject from a launch tube as on a submarine.
The test stand is at the east coast site of Sinpo, where North Korea has a naval shipyard and research institute.
Last week, the commander of U.S. forces in Korea said Pyongyang may be capable of fielding a nuclear-armed missile that could reach U.S. soil.