ABSTRACT In the prelude to the 2022 Russia–Ukraine War, American intelligence had concluded the invasion ‘might take a few days longer’ than Russians expected, but not much longer. The Russian Aerospace Forces was expected to eliminate Ukraine’s air defense and pave the way for Russian troops. What explains the failures of the Russian Aerospace Forces to acquire air superiority? I explore three causal factors to understand these failures – Russian military history and its impact on Russia’s air doctrine, Russian intelligence failures, and Ukrainian resolve and innovativeness. I also highlight the causal role played by the United States in sharing critical intelligence.