Iran has warned that vessels violating new Hormuz transit rules could face blacklisting alongside their flag, classification society and insurer; penalties could extend to other ships using blacklisted service providers, Nour News citing an official

Threats against the insurance and classification chain, rather than against hulls themselves, are a familiar escalation register around the strait: the mechanism is freight and insurance pricing, not physical closure, since blacklisting a vessel's P&I cover or flag makes transit commercially impossible even where it remains physically possible. Past episodes of this kind have tended to show up first in war-risk premia and charter rates on the Gulf routes, with crude and product tanker markets reacting before any actual interdiction occurs, and the distinction between rhetorical deterrence and enforceable policy has historically been the key question, as Iran-linked agencies have issued transit warnings repeatedly without systemic follow-through. The contagion clause, penalising other ships sharing a blacklisted insurer or class society, is the element that would widen the effect beyond the directly targeted tonnage if enforced, since a small number of providers dominate the relevant cover. The actors' prior form matters here: announcements channelled through security-affiliated outlets have usually preceded either negotiated de-escalation or isolated vessel seizures rather than sustained blockade. Follow-ons worth tracking are any published text of the transit rules themselves, guidance or rate action from the major P&I clubs and war-risk underwriters, and whether flagged tonnage actually alters routing or declares compliance.