Iran's Persian Gulf Strait Authority issues new rules for ships transiting through the Strait of Hormuz and warns vessels that violate Iranian protocols could face restrictions on subsequent voyages, including fines, detention or seizure

• Cargo owners are being told to check Iran's non-compliant vessels list before chartering ships, while any vessel conducting ship-to-ship transfers or other transactions with a blacklisted vessel will itself be added to the list.

Iranian assertions of jurisdiction over Hormuz transits have recurred for years, and the established pattern is that formal rule-making of this kind matters less for immediate flows than for the compliance burden it places on charterers and the ambiguity it creates around enforcement. The mechanism here is a blacklist architecture with secondary-liability features: vessels transacting with non-compliant tonnage risk designation themselves, a structure that mirrors sanctions contagion logic and tends to split the tanker market into compliant and grey-fleet segments, with the latter absorbing sanctioned barrels at discounted freight. Comparable episodes have historically played out through shipping costs rather than physical interruption: war-risk premia, hull insurance and freight rates on Gulf loadings reprice first, while outright transit disruption has remained the tail case given the share of global seaborne crude and LNG that passes the strait and the exposure of Gulf producers themselves to its closure. The prior form of the actors is episodic: advisory notices, occasional inspections and detentions of specific vessels on stated legal grounds, followed by quiet release or negotiation, rather than sustained interdiction. What is worth watching is whether the non-compliant list is actually published and enforced against named tonnage, any change in naval escort or insurance pricing from the major P&I clubs, and whether charterers begin declining Gulf fixtures, since those are the tells that distinguish bureaucratic posturing from an operational squeeze.