On the 28th, following surprise airstrikes by the U.S. and Israel on Iran, the Strait of Hormuz, which serves as a vital artery for global oil transportation, has entered a phase of effective blockade. While the Iranian authorities have not made an official declaration of a blockade, repeated radio warnings directed at commercial vessels have led to a notable decrease in shipping activity, with some tanker vessels turning around. Approximately 70% of South Korea's oil imports come from the Middle East, with most passing through this vital passageway.

According to Reuters, a representative from the EU Naval Force’s Aspides operation reported that the Iranian Revolutionary Guard has been issuing warnings via VHF radio to commercial vessels passing near the Strait, stating that "no ships can pass through the Strait of Hormuz." However, the official confirmation of these measures by Iran is still pending. The UK Maritime Trade Operations (UKMTO) has also received reports from multiple ships indicating they were notified that the Strait was closed. A semi-official Iranian news agency has reported that the Strait is essentially in a state of closure, emphasizing Iran's historical pattern of threatening to blockade the strait in response to military actions against it, despite not having executed a full blockade in the past.

Disruption in actual shipping operations is already occurring. Analysis of shipping tracking data by Bloomberg revealed that the Very Large Crude Carrier (VLCC) "KHK Empress," which was carrying Omani crude oil to Basra, turned around just before entering the Strait and headed back to the Arabian Sea. Other vessels laden with Saudi crude oil heading to China and Rotterdam have also halted at the entrance of the Strait. Major global energy companies like Shell have put chartered large tankers on standby near Iraq, while Japan's largest shipping company, Nippon Yusen (NYK), alongside Greek shipping authorities, has urgently instructed its vessels to avoid passing through the Strait of Hormuz. However, U.S. officials state that there is no evidence yet that Iran has implemented any physical blockades in the Strait, as some ships continue to transit at high speeds.