This article analyzes the 2014 Russian intervention in Ukraine as a prime example of autocratic diffusion-proofing. First, it provides examples to flesh out the relatively new concept of diffusion-proofing. Next, it reviews three bodies of literature — studies of realism, competitive authoritarian regimes and the decision calculus of authoritarian rulers—in order to identify key elements driving the Russian decision to invade Ukraine. Finally, it provides insight into how Russians developed their repertoire of intervention by relating the concept of diffusion-proofing to reputation-proofing. The article concludes by highlighting important implications for future studies of authoritarianism and international aggression.