Is Russia burning through air defense missiles at an "unsustainable rate"?

Kyiv — Russia is running low on a key type of missile interceptor, sources tell CBS News, which could be helping Ukraine launch effective strikes deeper inside Russian territory as analysts note a possible changing of the tide in Kyiv's favor more than four and a half years into the war. Moscow is experiencing a shortage of S-300 missile interceptors, three Ukrainian officials familiar with the country's intelligence estimates have told CBS News. The S-300, a surface-to-air missile system designed by the Soviet Union during the 1960s and 70s, has traditionally served as a vital component of Russia's air defenses against cruise and ballistic missiles. Throughout its war on Ukraine, Russia has turned to more advanced interceptors for that purpose, including the newer S-350, S-400 and Pantsir-S1 systems. But the S-300s have remained part of Moscow's defenses against Ukrainian missile and drone strikes. In 2025, estimates from Ukraine's intelligence services reported by The New Voice of Ukraine suggested Russia had more than 400 interceptors on hand for S-300PM and S-400 air defense systems. A Russian S-300V missile launcher operates during a show at the International Military Technical Forum, in an Aug. 17, 2022 file photo taken in Patriot Park, outside of Moscow, Russia. …