Ukraine's Deep Strikes Depleting Russia's S-300 Air Defense Missiles at 'Unsustainable Rate'

Ukraine's sustained deep strike campaign is depleting Russia's stockpile of S-300 air defense missiles faster than Moscow can replenish them, according to Ukrainian intelligence officials who spoke with CBS News. The S-300, a Soviet-era surface-to-air missile system developed in the 1960s and 1970s, has long formed a critical part of Russia's air defense network against cruise missiles, ballistic missiles, and drones. While Russia has increasingly relied on more advanced systems such as the S-350, S-400, and Pantsir-S1, the S-300 remains integral to its overall defensive posture.

Ukrainian officials cited by CBS News confirmed a "reduction in Russia's stockpile of S-300 surface-to-air missiles" without disclosing exact figures, though 2025 estimates suggested Russia had more than 400 interceptors available for S-300PM and S-400 systems. Rob Lee, a Russian military expert at the Foreign Policy Research Institute, told CBS News that Russia is expending air defense missiles "at a kind of unsustainable rate, because Ukraine can produce more deep strike drones than Russia can, in some cases, produce air defense missiles."

Multiple factors are accelerating the depletion. Ukraine has intensified direct attacks on Russia's air defense installations across occupied territories including Crimea, Luhansk, and the Dniester region. Additionally, Russia has repurposed some S-300 systems for offensive surface-to-surface strikes against Ukraine, supplementing ballistic missiles like the Iskander-M and Kinzhal. Ukraine has also forced Russia to expend interceptors defending against newer, faster drones equipped with jet engines that outperform earlier models.

Replenishing Russia's inventory faces significant obstacles. Ukrainian intelligence officials report that Moscow lacks critical components needed to manufacture interceptor missiles, including guidance seekers and control modules. Russia's ability to source these parts from Western and Chinese manufacturers has been hampered by long-standing international sanctions. Moscow is instead prioritizing production for more modern air defense systems to counter the drone threat.

Despite Russia's challenges, Ukraine faces its own air defense shortfall. Kyiv has warned of insufficient American PAC-3 interceptors—the most reliable defense against Russian ballistic missiles—while estimates suggest Russia may soon increase ballistic missile production to 600–800 units annually. Lockheed Martin, which manufactures PAC-3 interceptors for Ukraine, delivered only 620 worldwide in the previous year, highlighting a broader arms production imbalance in the conflict.