Anton Mardasov, an independent Russian analyst and non-resident scholar of the Middle East Institute's Syria program, noted that the "new wave of rumors" concerning an Iranian S-400 contract coincides with rumors of Iran deploying advanced indigenous air defense systems in Syria.
"Of course, it cannot be ruled out that Tehran did indeed demand S-400 deliveries from Russia for its support in the war in Ukraine through deliveries of kamikaze drones (loitering munitions)," he told me. "However, it is important for Iran to develop its own military-industrial complex, supervised by the IRGC (Islamic Revolutionary Guard Corps), and this military-industrial complex produces an analogue of the Russian S-300 complexes."
Mardasov noted that despite the suggestion of deeper cooperation from reports on the supply of S-400s and the deployment of Iranian air defense systems in Syria with tacit Russian consent, Iran and Russia have not clinched a full-fledged military alliance.
"It is clear that air defense supplies are not really a red line for Israel since these are really defensive weapons and they are purchased simply to have more advanced systems in service," Mardasov said. "But in a situation where Russia is somehow helping Iran to modernize its strike capability in view of its use in the Ukraine war, the supply of S-400 could upset the already fragile balance in Russia-Israel relations."