Over the past decade, China has grown increasingly concerned about its waning leverage over North Korea and inability to restrain Pyongyang’s nuclear ambitions. These worries have only intensified with North Korea’s dramatic tightening of ties with Russia this year.

Researchers at SI Analytics, a South Korean satellite imagery firm that uses AI technology to scour images, also confirmed the new construction at the February 11 plant, saying in a report on Monday that some of the construction near the loading area would likely be used to conceal the future operations of the factory from satellites.