Russia’s annexation of Crimea occurred after twenty years of relative peace and the apex (and failure) of pro-Russian sentiments within Crimea. Annexation is surprising for Putin’s willingness to pursue such risky actions, but also because it required elite support within Crimea. This article uses process tracing to test ethnonationalism in explaining support for Russia’s annexation against a rival explanation focusing on the role of criminality and crime (financial-criminal incentive structure). By exposing how and which elites defected in Crimea, the article demonstrates that elite breakage and realignments occurred within a financial-criminal incentive structure to motivate engagement in annexation. In turn, this article discusses its broader implications for understanding Russia’s full-scale war against Ukraine and the politics of conflict, nationalism, and the wider former Soviet Union.