[caww]

Here’s a better article on the fuel....could be they make it themselves...reading down page further gets pretty interesting..

https://www.nytimes.com/2017/09/17/world/asia/north-korea-rocket-fuel-missiles.html

[TigerLikesRooster]

China is responsible for helping N. Korea to build manufacturing infrastructure to produce nukes and missiles, allowing necessary materials and equipment to be procured in China and pass through Sino-N. Korean border.

Russia might be responsible for a sudden leap in NK's rocket technology.