As mentioned by @michaeldweiss on X:
Critical new report on the vulnerabilities of the Russian S-400. The platform’s electronics are heavily reliant on Rogers, a company in the U.S., with loose export controls and a Chinese subsidiary; and on one in Kazakhstan, which has not been sanctioned. Also, the S-400’s guidance and control systems are made at two facilities in Russia – both within striking distance of Ukraine’s Flamingo cruise missile



Some key points
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I am not sure I agree with RUSI that Russia is capable of sustaining this rate of loss of air defense systems, I can’t help but feel this article may have been partially in the works for quite awhile and the narrative in the last month or two has begun to shift to a point that while I don’t think any of the fundamental points of this article are wrong I do think it portrays Russia as much more capable of sustaining extensive air defenses losses than they are. The fact that Ukraine is able to hit these systems so regularly with cheap, inexpensive strike drones is itself a strategically unsustainable relationship for Russia and is indicative of the state of decay the Russian military is at. To be fair to the article it treats training as outside the scope of its consideration but I don’t know I just don’t think you can place training outside the scope of consideration when talking about air defense, air defense requires an ensemble of assets all working together that are trained in effectively collaborating to defeat waves of flying bombs, cruise missiles and other threats. It isn’t just that lots training is necessary to teach people how to know how to do their individual job with the equipment they are trained on in an air defense network, air defense is like making sure a boat has no leaks, it is a wholistic pursuit where if one part of the hull is bullshitting about not having a leak the whole ship sinks… and I think it is a very safe bet to say there is a metric fuckton of bullshitting about air defense in the Russian military (which isn’t to say that there aren’t also plenty of highly capable Russian air defenses and air defense crews especially on paper).