A Financial Times investigation published on September 1–2, 2026, has revealed details of a covert Russian-Iranian program launched in 2023 to develop advanced technology for hypersonic cruise missiles under the codename C430L.
According to the investigation, the cooperation goes beyond technology transfer and includes the direct involvement of specialized Russian engineers in developing a ramjet propulsion system — a key technology for propelling missiles at high speeds while maintaining low-altitude flight.
How Far Has Iran Come?
Information obtained by the Financial Times indicates that Iran has already manufactured and flight-tested the ramjet engine, while Russian engineers have provided assessments of flight-test data, including the fuel system, combustion stability, air intake and engine nozzle.
In April 2025, Russia also reportedly proposed sending approximately 24 Russian specialists to Iran for additional technical consultations.
Why Does It Matter?
For Iran, ramjet technology offers an opportunity to accelerate the development of a new generation of missiles combining high speed, low-altitude flight and reduced warning times for opposing defence systems.
This is particularly significant in the Persian Gulf, where U.S. naval assets operate relatively close to Iranian territory.
For Russia, providing this level of specialized engineering expertise suggests that military cooperation with Tehran is moving beyond weapons transfers toward the transfer of technological capabilities that could affect the regional deterrence balance.
And this is where the broader picture emerges.
Iran previously supplied Russia with Shahed drones and contributed to establishing their production inside Russia. In return, Moscow now appears to be assisting Tehran in a field that could give it an additional capability to challenge U.S. naval superiority in the Gulf.
The Equation for Washington
The issue is not whether Iran currently possesses an operational hypersonic weapon, but how quickly it may be approaching that capability.
If Tehran succeeds in transforming ramjet technology into an operational missile combining speed, maneuverability and low-altitude flight, it could put increasing pressure on the U.S. assumption that its sensor networks and layered defence systems provide American naval forces with a substantial margin of safety in the Gulf.
Moscow does not necessarily have to hand Tehran a finished missile; more consequentially, it may be helping Iran shorten the path toward producing one itself.