Russia’s S-400 air defence system has significant vulnerabilities, according to a new RUSI report.
The system’s electronics rely heavily on U.S. company Rogers, which has loose export controls and a Chinese subsidiary, while another critical supplier is based in Kazakhstan and remains unsanctioned.
The S-400’s guidance and control systems are produced at just two facilities in Russia, both within range of Ukraine’s Flamingo cruise missiles.
Like other Russian air defence platforms, the S-400 depends on foreign microelectronics, materials, and software, making it susceptible to sanctions, cyber attacks, and targeted strikes.
Exploiting these weaknesses could seriously disrupt Russia’s air defence capabilities and give Ukraine a strategic advantage in long-range strike operations.
The Western alliance may finally have a clear roadmap for dismantling Russia’s much-hyped air defense juggernaut, the S-400 Triumf, without firing a single shot.
A new research paper, released Friday by a leading London think tank, lays bare the structural weaknesses behind Russia’s flagship S-400 system, revealing that the weapon Moscow promotes as a self-sufficient technological marvel is, in fact, deeply vulnerable to disruption – both through sanctions enforcement and kinetic strikes.
The report, “Disrupting Russian Air Defense Production: Reclaiming the Sky, published by the Royal United Services Institute (RUSI), concludes that Russia’s ability to produce and sustain its most advanced air defense systems rests on fragile foreign supply chains, unsanctioned production nodes, and a manufacturing base increasingly within reach of Ukrainian long-range weapons.
In an interview with Kyiv Post on Friday, Dr. Jack Watling, one of the report’s authors and a Senior Research Fellow for Land Warfare at RUSI, said the findings point to a broader strategic failure by Ukraine’s partners to turn knowledge of Russian vulnerabilities into coordinated action.
“This research paper examines the vulnerabilities in Russia’s air defense production ecosystem,” Watling said, “highlighting critical dependencies on foreign technologies, materials, and supply chains.”
Disrupting those dependencies, he argued, is central not only to Ukraine’s battlefield prospects but to European security more broadly.
At the core of the S-400’s vulnerability is its reliance on foreign-made microelectronics, including materials produced in the US. This dependency is a key choke point for Russian production.
The report identifies RO4003C, a high-frequency laminate manufactured by US-based Rogers Corporation, as a critical component used in the system’s radar architecture.
Such materials are essential for modern phased-array radars but are not produced at scale inside Russia.
Despite US export controls, the report documents how Russian defense firms continue to obtain these components through intermediaries – primarily via China and Hong Kong.
In some cases, Chinese vendors openly advertise materials for use in Russian radar systems, highlighting what the report describes as weak enforcement rather than weak legislation.
Watling said this reflects a broader problem with current sanctions policy, emphasizing that it is not the laws but their execution that is failing.
“There is a need to expand enforcement and strengthen cooperation on enforcement,” he said, adding, “It’s all very well passing a sanction, but if we still see fairly obvious circumvention getting through, it suggests that countries are not being vigilant enough in making sure that sanctions are respected.”
He emphasized that these enforcement gaps are often the result of insufficient intelligence sharing and limited capacity among partner states, rather than a lack of legal authority.
Beyond Western electronics, the report uncovers a critical dependency on raw materials sourced from Central Asia – specifically beryllium oxide ceramics, which are essential for high-performance radar components.
This provides Moscow with another geographical weak spot. According to RUSI, Kaz Ceramics LLP, based in Kazakhstan, is a key supplier of these materials for Russian air defense production.
The company and its affiliates are described as being aware of sanctions risks and actively restructuring logistics to avoid scrutiny.
Shipments are increasingly routed through a Russian affiliate, LLC Zenit, based in Novosibirsk, allowing supplies to reach major Russian defense importers without triggering sanctions.
Watling cautioned that simply sanctioning such entities may not be sufficient and argued for a more creative approach.
“If I sanction this Kazakh factory that produces the beryllium oxide ceramics for the radar, it will probably still sell to Russia, because that’s its only viable customer,” he said. “A much more effective approach may well be to outspend the Russians and just buy the material.”
Other options, he added, could include acquiring stakes in vulnerable firms or otherwise removing key inputs from Russian reach – an approach that requires coordination and creativity rather than symbolic measures.
Perhaps the report’s most consequential insight is that Russia’s air defense production is not only vulnerable to sanctions but is physically exposed to Ukrainian long-range strikes.
The facilities responsible for manufacturing S-400 guidance and control systems are concentrated at a small number of sites, several of which are within range of Ukraine’s expanding deep-strike capabilities.
But Watling stressed that strikes alone are not enough; without concurrent economic action, the effect is only temporary.
“If the Ukrainians strike a factory, that might take the factory offline for three months if the machine tools are damaged,” he said, adding, “But if the factory is unsanctioned, then they can just buy more machine tools, and you’ve only delayed production for a short time.”
The real impact, he argued, comes from sequencing military action with diplomatic and economic measures – striking facilities first, then preventing their recovery.
“At the moment,” Watling said, “there are lots of militaries that speak to the Ukrainian military, and our foreign offices speak to the Ukrainian foreign office. But there is not the sequencing between what the Ukrainian military does and what our foreign offices do in terms of sanctions and enforcement.”
The report also points to Ukraine’s growing indigenous strike capabilities, including the newly disclosed Flamingo cruise missile, which Ukrainian sources claim has a range of up to 3,000 kilometers and a heavy warhead designed for hardened targets.
This new arsenal makes the S-400’s supply deficit a critical factor.
If production expansion is disrupted, Watling said, Russia faces a mounting problem: an inability to replenish air defense interceptors at the pace required to counter Ukraine’s long-range campaign.
“The Russians want to enable production to meet the rate of intercept expenditure to defeat Ukraine’s long-range strikes,” he said. “But at the moment, there’s a deficit.”
Preventing the expansion of production capacity, he added, could eventually produce a shortage of air defense missiles, making Ukrainian strikes progressively more effective.
Implications beyond the battlefield
The findings carry implications well beyond Ukraine’s borders. Russia is already behind schedule on foreign S-400 deliveries, including contracted systems for India. Watling said continued delays could undercut export revenue that Russian manufacturers rely on to stay afloat, directly threatening the industry’s financial stability.
“If Russia doesn’t get foreign sales, it will struggle to generate the revenue in this industry to keep up production,” he said, noting that several companies involved are already financially vulnerable.
The report also raises questions for existing S-400 operators about Russia’s ability to supply reloads and provide long-term maintenance during a crisis, particularly if key components are unsanctioned, exposed, or already compromised by foreign insight into the system’s design.
Watling confirmed that the research team identified more than 70 major vulnerabilities across Russia’s air defense production chain, many of which were deliberately excluded from the public report to avoid tipping Moscow off before action is taken.
“The key thing,” he said, “is understanding what actually takes these capabilities out of play and then taking the appropriate action – so that we actually have a disruptive effect, rather than just a performative effect.”
Once marketed as an impenetrable shield, the S-400 is now revealed as something more brittle: a system propped up by global supply chains, narrow production bottlenecks, and political hesitation in Western capitals.
The choice facing Ukraine’s partners is whether to turn this knowledge into action. Whether those weaknesses are exploited may determine not just how the war is fought, but how, and on whose terms, it eventually ends.
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