An investigation by NK News's sister site NK Pro on Monday raised questions about how and why – in light of United Nations sanctions – Air China is able to purchase jet fuel when its aircraft go to North Korea.

Photos obtained during the NK Pro investigation showed that on at least seven times since 2016, the Chinese flag carrier's jets were photographed connected or near to Air Koryo fuel tanker vehicles at Pyongyang's Sunan International Airport (FNJ).