Iran's counter-move to the opening strikes was to shut the world's most critical oil chokepoint. The Strait of Hormuz — through which 20 percent of the world's daily oil supply and 20 percent of global LNG transits — was declared closed to all commercial shipping on March 4. Over 150 tankers anchored outside the strait rather than risk attack. Maersk, MSC, CMA CGM and Hapag-Lloyd all suspended transits. The US imposed a formal naval blockade on April 13. China, which imports 40 percent of its oil through the strait, entered emergency reserve protocols. Japan and South Korea followed.
Data: US Congressional Research Service · EIA · UK House of Commons Library · Carra Globe shipping analysis (April 2026)