Sanctions rely heavily on financial system leverage: The U.S. enforces sanctions primarily through the global dominance of the U.S. dollar and financial intermediaries, rather than costly physical blockades alone.

Maritime insurance and classification are key sanction enforcement mechanisms: Withdrawal of insurance and certification by major Western bodies raises risks for ships linked to sanctioned countries, restricting their operations and flag registrations.

Shadow fleets and alternative flag states reveal circumvention attempts: Countries like Venezuela, Russia, Iran, and likely China collaborate to use shadow fleets and smaller classification societies to evade sanction constraints, forcing the U.S. to intensify physical enforcement.