China's Refinery Protection Strategy Reflects Broader Sanctions Evasion Pattern China's Commerce Ministry blocking US sanctions against five refineries continues a two-decade pattern: Chinese entities process roughly 40% of Iran's crude oil exports despite US restrictions. This mechanism—using Chinese middlemen and state-owned refineries to obscure supply chains—has enabled Iran to maintain $50-60 billion in annual oil revenues since 2015, circumventing sanctions designed to pressure nuclear negotiations. The maneuver matters because it demonstrates how US unilateral sanctions increasingly depend on third-party enforcement; when major trading partners refuse cooperation, sanctions lose structural power, reshaping geopolitical leverage in energy markets and nuclear diplomacy.