The Los Angeles Times obtained satellite images indicating that since 2012, at least three islands have been built with rectangular lots, paved roads and other markers of a military installation.
"We can't make definitive statements as to what these islands are being used for," Ryan Barenklau, an executive with intelligence firm Strategic Sentinel, told the Times. "Military use is likely. Roads on the islands feature wide turns, indicating that they could be used for various military vehicles."
Barenklau also suggested that light patches could indicate heat-resistant cement ideal for launch pads, and noted observation areas, possibly for the use of North Korean leader Kim Jong-un.
It has been suggested that Pyongyang may have taken a cue from Beijing, which is accused of building military installations on artificial islands the South China Sea, drawing the ire of the US and its allies despite its insistence that it has done nothing wrong.
In late March, Chinese Defence Ministry Spokesman Wu Qian told reporters, "There is no such thing as man-made islands … Most of the building is for civilian purposes, including necessary defensive facilities."
Tensions continue to simmer in the region, as the Democratic People’s Republic of Korea (DPRK) publicly blasts ally and trading partner China for agreeing to tougher sanctions against Pyongyang, while the US and South Korea continue annual joint military drills, complete with a US Navy carrier strike group and nuclear powered submarine stationed near the Korean Peninsula.
Pyongyang has called US President Donald Trump a "mere beginner insofar as its ignorance of its rival was concerned" and warned that "China had better ponder over the grave consequences to be entailed by its reckless act of chopping down the pillar of DPRK-China relations."