Russia has been secretly assisting Iran in developing supersonic cruise missile technology through a covert program called C430L, according to a Financial Times investigation. Since 2023, Russian missile experts have reportedly helped Iran improve ramjet engines directly linked to the technology used in the P-800 Oniks ramjet engine, which allows missiles to travel at several times the speed of sound and potentially threaten U.S. warships and land targets.

The program reflects growing military cooperation between Russia and Iran, following Iran’s supply of drones for Russia’s war in Ukraine. Leaked documents indicate that Russian engineers provided technical guidance, reviewed Iranian flight-test data, and continued working with Tehran through 2026. Although Iran has tested the technology, there is no evidence that a Russian-assisted supersonic cruise missile has yet been deployed.

Analysts say the technology transfer could significantly strengthen Iran’s military capabilities and represents one of the most important examples of Russian military assistance to Iran in recent years. If successful, it could give Iran a powerful new weapon system and boost its long-term defense industry.