US Naval Blockade Cuts Off Iran's Oil Revenue as Strait Gamble Reverses

A US naval blockade that took effect at 14:00 GMT on Monday has cut Iran's primary oil export route through the Strait of Hormuz, threatening to choke off revenue that had paradoxically risen during the preceding weeks of conflict. The timing is pointed. Iran was exporting 1.71 million barrels per day as of mid-April, according to Kpler data—marginally above the 1.68 million bpd average for 2025. From March 15 to April 14, Tehran shipped 55.22 million barrels, earning an estimated $4.97 billion at $90 per barrel, a 40 percent jump over pre-war monthly revenues of $3.45 billion. That income stream is now at risk. The distinction between sanctions and a physical blockade matters. Iran has spent years routing around sanctions through shadow tanker fleets and alternative buyers. A blockade prevents vessels from loading and departing in the first place. Iran's armed forces have called the action illegal, but legal protests do not move tankers. Through the early weeks of the conflict, Iran had closed the strait to most traffic following the February 28 start of US-Israeli military operations, allowing passage only to countries with individual arrangements. Iranian exports continued throughout, with light, heavy and Forozan blend prices frequently exceeding $100 per barrel during that period. Some analysts estimate Iran could route surplus crude into onshore storage for roughly two months before capacity is exhausted, at which point production curtailments become unavoidable. Cuts of that scale—potentially affecting the full 1.7 million bpd export volume—would tighten an already constrained global market. Russia has benefited from the disruption. Chatham House analysis shows that surging energy prices boosted Russian budget and export revenues at a moment when Western sanctions were squeezing output. Before the Iran conflict escalated, Russian oil export revenues had fallen to $9.5 billion in February 2026, the lowest since 2022, with volumes down to 6.6 million bpd—850,000 bpd below January. The merchandise trade surplus in January stood at $6.5 billion, down a third month-on-month. Higher Gulf prices reversed much of that deterioration. The Carnegie Endowment notes that even a short-lived crisis has exposed how thin the margins of global energy trade actually are. Iranian shipments to China appear to be continuing for now, and those tankers are not being systematically stopped. How rigorously the blockade is enforced will determine everything. The two-month storage window is the number to watch. If enforcement holds that long, Iran faces forced production shutdowns. The regime's financial runway depends on whether alternative export corridors emerge and how long elevated global prices compensate for lost volume. Any wider escalation involving Gulf producers without pipeline alternatives to the strait would tighten supply further and add another leg to the price move.