The Russian Group for Solidarity with the DPRK said this in a statement on March 15.

The statement extended warm congratulations to the Korean people upon succeeding in developing the heat-resisting materials for rocket by their own efforts and technology and realizing the local production of them.

It went on:

It's marvelous to see the DPRK making remarkable scientific and technological successes despite the severest economic sanctions.

The Korean people are countering the U.S. imperialists and south Korean puppet forces' moves for provoking a nuclear war with their general offensive of the scientific and technical revolution.

We support the DPRK's policy of attaching importance to science and technology that is dealing a deadly blow at the enemy with its scientific and technical revolution.