The United States Treasury has issued a stark warning to the global shipping industry: any company paying fees to Iran for safe transit through the Strait of Hormuz will face punitive sanctions, even if the payments are disguised as charitable donations to organisations such as the Iranian Red Crescent Society. The advisory, released by the Office of Foreign Assets Control on Friday, represents a significant escalation in Washington’s efforts to enforce its maximum pressure campaign and to counter Tehran’s de facto blockade of one of the world’s most vital maritime chokepoints. Roughly a fifth of all seaborne crude oil and liquefied natural gas flows pass through the strait under normal conditions, making any disruption a matter of acute concern for energy markets from London to Tokyo.

The crisis was triggered by a series of US and Israeli strikes on Iranian targets on February 28, after which Tehran effectively closed the waterway to routine traffic by attacking vessels and threatening further action. Iran subsequently offered selected ships a rerouted passage closer to its coastline, demanding fees — sometimes framed as donations to state-linked charities — in exchange for safe conduct. Viewed from Washington, these tolls constitute a form of extortion that directly flouts international maritime law and enriches a regime already subject to sweeping sanctions. Analysts in London note that the Treasury’s warning is also an attempt to close a loophole that could allow Iran to generate hard currency while maintaining the pretence of humanitarian relief.

Tehran’s response has been defiant. Brigadier General Mohammad Jafar Asadi, deputy commander at Iran’s joint military headquarters, declared over the weekend that armed forces remain on high alert and that a resumption of hostilities with the United States and Israel is “likely”. His remarks, carried by the semi-official Fars news agency, accused Washington of lacking genuine commitment to diplomatic solutions and of using media narratives to stabilise oil prices while distancing itself from the consequences of its own strikes. The implication, as read by observers in the Gulf, is that Iran sees the sanctions warning as a further escalation, not a deterrent. The Strait of Hormuz remains a tinderbox: with both sides refusing to back down, the risk of a direct confrontation rises by the day. For global energy traders and maritime insurers, the immediate calculus is clear — compliance with US sanctions may be legally prudent, but it does nothing to secure a safe passage through a strait that has become the focal point of a much wider struggle for regional dominance.