North Korea's latest Hwasong-18 intercontinental ballistic missile — its first ICBM to use solid rocket fuel — has reignited debate over possible Russian links to the nuclear-armed state's dramatic missile development.

In a report published on Thursday by the Washington-based Center for Strategic and International Studies, Theodore Postol, professor emeritus at the Massachusetts Institute of Technology, argued that the Hwasong-18 ICBM is likely the result of technical cooperation sourced to Russia.

The Hwasong-18 has been tested twice, including on July 12 in what was the longest flight time ever for a North Korean missile test.