Russia has been quietly helping the Islamic Republic close one of the most important gaps in its missile arsenal: developing a ramjet-powered cruise missile capable of sustained flight at several times the speed of sound. The covert effort, code-named C430L, could eventually give Tehran a far more dangerous weapon against U.S. naval forces and fixed land targets, according to a Financial Times investigation based on leaked Russian correspondence, travel records and military patents.

The program began in 2023 and was formalized later that year through Rosoboronexport, Russia’s state arms exporter, and NPO Mashinostroyenia, one of Moscow’s most experienced missile-design organizations. This was not simply a sale of finished weapons. Russia reportedly sent senior engineers into Iran to help Tehran overcome difficult technical obstacles and build the capability itself.

Among those involved were Alexander Dergachev, a chief designer for sea-launched missiles; Alexander Chebakov, a specialist in supersonic ramjet propulsion; and Yuri Prokhorchuk, head of NPO’s aerodynamics and ballistics department. Rosoboronexport official Vladislav Kuzmichev later negotiated the C430L contract with Iran’s Ministry of Defense and Armed Forces Logistics.

By 2025, Russian engineers were analyzing extensive technical material supplied by Iran and sending back detailed questions. Correspondence from June 2026 reportedly showed the two sides discussing the program’s next phase, indicating that the cooperation continued even after the outbreak of direct fighting involving Iran, Israel and the United States.

A ramjet uses a missile’s forward speed to compress incoming air and sustain powered flight after an initial booster accelerates it. That combination can produce a cruise missile traveling several times faster than sound, drastically reducing the time available for a ship or air-defense battery to detect, track and intercept it.

Iran already possesses an extensive ballistic-missile arsenal and produces slower cruise missiles, but developing a reliable ramjet-powered supersonic weapon has remained a major technical challenge. Tehran displayed a domestically developed ramjet engine in 2019 and later claimed that the IRGC had begun testing a prototype supersonic cruise missile.

The FT investigation found that Iran built and tested the propulsion system involved in C430L. However, there is currently no evidence that a completed Russian-assisted missile has entered operational service. Its range, guidance system, warhead and intended launch platforms also remain unknown.

The Russian organization involved is no minor contractor. The U.S. Treasury has sanctioned NPO Mashinostroyenia since 2014 and describes it as a leading Russian rocketry company responsible for cruise-missile systems launched from surface, underwater and ground platforms. It has also worked on intercontinental ballistic missiles and programs connected to Russia’s strategic nuclear forces.

The reported program reflects the increasingly transactional military alliance between two regimes confronting the West. Iran supplied Russia with Shahed attack drones and the technology needed to establish Russian production lines for them. Moscow now appears to be providing Tehran with something potentially more enduring than individual weapons: the engineering knowledge needed to design and manufacture an advanced missile domestically.

Russia and Iran formalized their expanding relationship through a 20-year strategic partnership that includes closer defense cooperation. The missile revelations also emerged as Vladimir Putin publicly reaffirmed Moscow’s support for Iranian President Masoud Pezeshkian and promised continued assistance despite U.S. pressure.

“A program like this would require political clearance from the very top in Russia,” missile expert Fabian Hinz told the Financial Times.

For Israel and the United States, the danger is larger than one potential missile. A finished weapon can be intercepted or destroyed. Engineering knowledge can be reused, improved and incorporated into future systems.

No operational C430L missile has been confirmed. But the leaked records indicate that Moscow is helping the Iranian regime move beyond importing advanced weapons and toward mastering a class of missile specifically suited for threatening warships and striking land targets.