Iran's Hormuz Blacklist: New Risks for Oil and Shipping
Iran has escalated its campaign to control traffic through the Strait of Hormuz by publishing a blacklist of 45 tankers. The vessels, named by the newly created Persian Gulf Strait Authority, face fines, detention, and cargo confiscation if they attempt to transit or engage in ship-to-ship transfers. The warning was issued on August 24, days after the United States threatened Tehran with the toughest sanctions in history.
The listed ships include very large crude carriers, LNG and LPG tankers, and clean product vessels. Owners affected include ADNOC Logistics and Shipping, its subsidiary Navig8 Tankers, Saudi Arabia's state carrier Bahri, as well as Klaveness Ship Management, Stolt Tankers, and South Korea's Sinokor. Any vessel caught conducting ship-to-ship transfers with a blacklisted ship could itself be added to the list, according to the authority's X post.
The blacklist lands at a moment when the strait is effectively closed to commercial shipping. Iran's deputy foreign minister stated on August 26 that the waterway remains "militarily closed" despite a joint announcement with Oman about a temporary maritime corridor and joint mine-clearing project. IMF PortWatch data shows that on August 23 only three commercial vessels transited the strait, compared with a pre-crisis average of 85 per day. That is 4 percent of normal traffic.
War-risk insurance premiums for tankers have surged to 40 times pre-crisis levels, with six protection and indemnity clubs withdrawing cover entirely. Most of the world's largest container carriers have stopped using the strait, rerouting Asia-Europe traffic around the Cape of Good Hope and adding roughly two weeks to each voyage. Spot war-risk quotes for a very large crude carrier voyage climbed from about $250,000 to $10 million.
Oil prices have been volatile. Brent crude fell 5.3 percent on August 23 and another 5.56 percent the following day, settling at $86.98. West Texas Intermediate stood at $80.84. U.S. Energy Secretary Chris Wright claimed that thanks to the U.S. Navy, the seven-day average of oil leaving the strait exceeded 8 million barrels a day. However, independent tracking shows that throughput remains severely compressed.
The Gulf supplied roughly 20 percent of the world's daily crude oil and liquefied natural gas before the conflict disrupted traffic beginning in late February 2026. The current crisis started when U.S.-Israeli airstrikes triggered Iran's Islamic Revolutionary Guard Corps to close the strait. A formal closure declaration followed in early March. A U.S.-Iran ceasefire brokered in June collapsed within days, and both sides have since resumed attacks.
The blacklist adds a new layer of legal and commercial risk. Ship owners whose vessels are named face not only the threat of seizure but also potential disruption to their insurance and chartering arrangements. Any ship-to-ship transfer with a blacklisted vessel could trigger secondary sanctions or additional costs. The Persian Gulf Strait Authority said cargo owners should refer to an updated list of non-compliant vessels and that ships seeking removal must file a formal request with Iranian maritime authorities.
Uncertainty remains high. Iran has not spelled out the specific rules it says vessels have broken, beyond a general requirement to obtain clearance and pay for security services. The actual enforcement of fines and confiscations has yet to be demonstrated. But the combination of a militarily closed strait, prohibitive insurance costs, and now a targeted blacklist means that any tanker operator or cargo owner moving oil or gas through the Persian Gulf faces unprecedented risk.