Russia has been secretly helping Iran develop advanced supersonic cruise missiles under a multiyear covert programme codenamed “C430L,” in what experts say could be one of the most significant known transfers of strategic military technology from Moscow to Tehran, the Financial Times reported.According to the FT’s investigation, which is based on leaked Russian correspondence and an analysis of military patents, the programme began in 2023, well before the ongoing US-Iran war, but has continued into the current conflict in the Middle East.The report noted that the C430L programme is primarily aimed at helping Iran develop a ramjet propulsion system, an engine that enables a cruise missile to sustain speeds several times faster than the speed of sound. Missile and military experts say the technology was almost certainly intended for anti-ship and land-attack cruise missiles.“This is the transfer of a highly strategically sensitive military technology from Russia that the Iranians have wanted to acquire for decades. A programme like this would require political clearance from the very top in Russia,” Fabian Hinz, an expert on Iranian missiles, told FT.Tehran is reported to have built and flight-tested the ramjet propulsion system, although there is no evidence that a Russian-assisted supersonic cruise missile has been deployed so far.
Why supersonic cruise missiles
Supersonic cruise missiles combine high speed with the ability to fly at low altitudes, reducing the time available for sophisticated air and missile defence systems to detect and intercept them. This is particularly relevant for Iran in the Gulf, where the US and its regional allies operate advanced land- and sea-based defence systems.“For the Iranians, this would give them a qualitatively new strategic weapon system that could threaten US Navy vessels,” Jim Lamson, a former Iran-focused military analyst with the CIA, said.Russia’s state arms exporter, Rosoboronexport, arranged the programme and co-ordinated the project with NPO Mashinostroyenia, a Russian rocket design bureau.Washington sanctioned NPO Mashinostroyenia in 2014, describing it as a major Russian rocketry company involved in cruise missile systems launched from ships, submarines and ground platforms, as well as work supporting Moscow’s strategic nuclear forces, including intercontinental ballistic missiles.Leaked travel records show that Russian arms export officials and several senior NPO Mashinostroyenia engineers made repeated trips to Iran before the C430L contract was formally signed with Tehran’s Ministry of Defence and Armed Forces Logistics in November 2023.
How project C430L unfolded
C430L involved some of NPO Mashinostroyenia’s most senior missile engineers, several of whom made repeated trips to Tehran in the lead-up to the formal signing of the contract.By 2025, NPO Mashinostroyenia had received a large cache of Iranian technical material on the ramjet propulsion system. Russian engineers analysed data from an Iranian flight test and sent Tehran a detailed list of questions about the system’s performance.They sought information on changes to the fuel system, combustion stability, air intake and engine nozzle. They also wanted to know whether the ramjet had continued operating after the telemetry provided by Iran — data showing the engine’s performance during flight — ended less than a minute into the test.In April 2025, Rosoboronexport proposed sending a delegation of about two dozen Russian specialists to Iran for technical consultations under C430L. The same correspondence asked Tehran to respond to the engineers’ questions about the flight-test telemetry before the proposed visit, linking the mission directly to the technical assessment of Iran’s propulsion system.The leaked correspondence shows that the C430L programme continued into 2026, after the start of the US-Israeli war against Iran, with Moscow preparing technical reports for Tehran and the two sides discussing the next phase of development.A June 2026 letter from Rosoboronexport showed that the parties were still negotiating elements of the next phase and planning further discussions on Russian technical reports. However, it remains unclear whether that phase of the programme has begun.