Satellite imagery appears to indicate that North Korea is working at equipping submarines with missile-launching capabilities, analysis published Thursday said.

In an analysis published at 38 North, Joseph Bermudez wrote that the conning tower of a submarine first seen in July may contain vertical launch tubes for ballistic or cruise missiles. Also, the satellite imagery reveals the North to have invested a considerable amount in upgrading its Sinpo South Shipyard, indicating a major naval development program, possibly relating to submarines.