This paper asks whether the United States and the European Union, despite divergent economic exposure and institutional design, can sustain a coherent sanctions strategy toward Russia, and how that divergence shapes the regime's effectiveness. It proceeds through a structured comparison across three policy domains — energy, finance, and immobilized sovereign assets — drawing on the literatures on economic statecraft, energy security, and financial-network theory, and on transaction-level, macroeconomic, and legal evidence from 2022 to early 2026. The analysis finds, first, that the United States' position as a net energy exporter enabled rapid embargoes, whereas the EU's import dependence produced a slower, phased decoupling. Second, US financial measures operated extraterritorially through dollar centrality and centralized OFAC enforcement, while the EU relied on regulatory jurisdiction over SWIFT but enforced through fragmented national authorities; a Gazprombank carve-out preserved the energy-export inflows that offset the intended balance-of-payments shock. Third, in the dispute over frozen assets, EU custodial institutions bear the legal and retaliatory exposure that the United States advocates from a position of relative insulation. The findings indicate that the regime's effectiveness is constrained less by the design of individual measures than by uneven enforcement and an asymmetric distribution of risk; absent institutionalized burden-sharing, its durability and credibility are likely to weaken.