'Rocket Engine 250', GRAU index: 8D518) is the base version of a dual-nozzle family of liquid-fuel rocket engines, burning a hypergolic mixture of unsymmetrical dimethylhydrazine (UDMH) fuel with dinitrogen tetroxide (N2O4) oxidizer in a gas-generator open cycle.

[7] The RD-250 was developed by OKB-456 for Yangel's PA Yuzhmash ICBM, the R-36 (8K67).

This transfer would explain the rapid progress of North Korea in the development of two new missiles: the intermediate-range Hwasong-12 and the intercontinental ballistic missile (ICBM), Hwasong-14.

Thus it is believable that complete hardware could have been bought on black market and directly shipped to North Korea, by Russia or Ukraine.

[10] Conversely, there is analysis[11] (made by two Ukrainian authors) suggesting an alternative mechanism for North Korea to receive R-36 missile engines, or an entire missile, from USSR or Russia.