May 2 (UPI) -- Recent satellite images show North Korea may be steadily building up its submarine-launched ballistic missile program.
The images from April 19 are aerial shots of Nampo Naval Shipyard, on the western coast of North Korea, writes Joseph S. Bermudez Jr.
The barge is "identical" in size and layout to the original barge that was first identified in 2014, according to the analyst.
The first barge was found at Sinpo South Shipyard on the east coast where as many as six SLBM launches took place since 2014.
"Both of these barges are very similar in size and layout to the old Russian PSD-4 submersible missile test stand barges," Bermudez writes. "Barges such as these are used by navies to conduct underwater tests of new and modified submarine missile launch tubes and launch systems, as well as to conduct initial missile test launches before these systems are installed in a submarine."
The second barge was likely acquired from overseas, the analyst added.
While North Korea may have acquired the barges simultaneously, there is a greater likelihood the "second barge seems to have been acquired three years after the first," the analysis read.
That means over time North Korea stepped up plans to accelerate its SLBM test program, in order to "include a west coast component or develop new SLBM designs."
In 2016, North Korea tested SLBMs in April, July and August. The missile tested in August flew more than 300 miles.
North Korea may have also undertaken a SLBM test in December, as part of Pyongyang's plan to secure the ability to "cold launch" through a vertical launch system, in which the missile is ejected by gas.