Iran Announces Full Closure of Strait of Hormuz Following US Strikes

Impact verdict

High impact. A sustained Strait of Hormuz closure would disrupt an estimated ~20% of seaborne global oil flows, directly exposing marine hull (vessels in transit, possible interdiction), marine cargo (crude and LNG cargoes at risk), energy (offshore platforms, refineries, pipeline throughput), war risk (premium spikes, additional premium notifications, vessel seizures, trading-warrant cancellations, possible interdict reports), and political violence/terrorism lines. Iranian reassertion of regulatory authority over Hormuz shipping, corroborated reports of a tanker strike, and continued US-Iran hostilities support material war-risk and marine market repricing. Severity banding is supported by the named insured-industry figure of four weeks of oil supply under a sustained closure and corroborated mainstream reports of strikes and Iranian official statements. Limits: Whether Iran can sustain full interdiction, duration of any disruption, the specific US targets struck, the reliability of the reported tanker interdict, the current physical closure status (transit reportedly resumed), and the status of the US-Iran MOU remain unverified or contested across sources.