Iran Says It Will Declare an Exclusion Zone Reaching Into the Strait of Hormuz and Blacklist Ships That Enter It

Iran said on September 7 that it will declare an "exclusion zone" covering the approaches to the Strait of Hormuz. Mohsen Rezaei, the newly appointed head of Iran's Supreme National Security Council and a former commander of the Islamic Revolutionary Guard Corps (IRGC), told Iran's state broadcaster that the zone would be announced in the coming days and weeks and "will begin from the line of the U.S. naval blockade, extend toward the Strait of Hormuz, and from this side continue into the Persian Gulf." Any ship that enters the area intending to transit the strait and is identified "will be placed on our sanctions list," he said, according to the Associated Press account carried by PBS. Rezaei gave no coordinates, no date and no description of how Iranian forces would enforce the zone, Fortune reported. Nothing is yet in force. Tehran has stated an intention, and the practical question is whether Iran can turn a declaration into interdiction at sea.

The statement came a day after the exchange moved from commercial ships to warships. The IRGC said on September 6 that its aerospace force fired ballistic missiles at a United States aircraft carrier and a guided-missile destroyer near the strait, and claimed both warships were damaged and left the area, answering American "harassment" of Iranian shipping and the blockade of Iranian oil exports, Al Jazeera reported in its running coverage. United States Central Command has not acknowledged damage to either vessel. It said the two ships evaded multiple Iranian attacks and that no American personnel were harmed. Neither side's account has been independently verified.

American forces struck three Iranian crude carriers on September 5. CENTCOM said it permanently disabled the M/T Downy off Kharg Island and the M/T Stark 1 near Jask, and destroyed the M/T Kylo in the Gulf of Oman, CNN reported. Admiral Brad Cooper, the CENTCOM commander, said the message to the IRGC was that if it shot at two American ships, the United States would take out three of Iran's, according to the Associated Press account carried by PBS. That is a wider response than the tanker-for-tanker policy a US official described to Axios last week. Iran's state broadcaster said Iranian forces then targeted three oil tankers and three American-linked vessels. Indian and Gulf outlets have carried the exclusion-zone plan as the next stage of the same sequence, Business Standard among them.

Behind the exchanges runs a quieter operation that determines whether the strait works at all. The Financial Times described US Navy divers, small boats and remotely operated robots making covert night trips into the channel to dispose of mines. Iran has said two tankers struck naval mines there. The American military has escorted convoys through the passage, including one group of 40 commercial vessels carrying 18 million barrels of oil, and negotiations remain stalled in a war now in its sixth month, The Hindu reported.

Prices have not yet registered either the attack on the warships or Rezaei's announcement, because both came after the last close of the week. Brent crude traded at about $96.28 a barrel on September 4, up 0.80 percent on the day, according to Trading Economics, after gaining more than 7 percent across a week of exchanged strikes, CNBC reported. Iran has been unable to export crude since July under the American blockade, and other producers are covering that lost supply at a higher price. The cost that a declared zone would move first is insurance rather than crude. War risk cover for a Gulf transit already runs between 3 and 10 percent of hull value, against 0.25 percent before the war, The National reported, and underwriters have withdrawn cover outright at earlier points in the conflict, as Al Jazeera documented. Escorting convoys, sweeping mines and insuring hulls through a contested strait adds a standing cost to every barrel and every cargo of liquefied natural gas that leaves the Gulf, and importers in Asia and Europe pay it rather than the parties fighting.