The analysis examines the architecture of the OFAC sanctions regime, including primary and secondary sanctions, the SDN List, the concept of blocking, the 50 percent rule and the role of a U.S. nexus in cross-border transactions. The authors highlight the practical implications for Romanian and European companies, especially in commercial relationships, financing structures, supply chains and international payments. The article underlines the need for careful sanctions screening, beneficial ownership checks, documented due diligence and a compliance process adapted to the company’s risk profile.