Over the past ten days, the grammar of Hormuz strait control has changed. What Iran did in February was close the strait. What Iran is doing in September is declaring that it will operate it. The difference may look small, but I read this shift as the most consequential change of the war so far. A fight over breaking a door eventually ends. A fight over posting a price list on that door tends not to.
On 9 September, Islamic Revolutionary Guard Corps spokesman Brig. Gen. Hossein Mohebbi announced that the waters running from Chabahar through the Sea of Oman and the Arabian Sea would be designated a “sanctions zone.” Vessels that enter it, he said, will not be able to use the Strait of Hormuz on their next passage, and will be denied port, insurance and other required services. A country under sanctions has begun issuing sanctions lists of its own. This is the scene I want to unpack.
- Iran’s September measures shift Hormuz strait control from blockade to a claim of passage administration. The contest has moved from force to rules.
- The US response has mutated symmetrically into “tanker for tanker” — not destruction so much as the steady removal of the other side’s export assets.
- Transit indicators tell conflicting stories. Official statements describe recovery; ship counts describe collapse. The market priced the latter.
- The IAEA’s 9 September referral to the Security Council is unlikely to produce enforceable sanctions. It will, however, stand as a record.
- The variable to watch from here is not interception rates but insurance premiums and third-country seafarer deaths.
Three changes of grammar in six months
Anyone who has followed this war from the start will have felt the phase shift more than once. I break it into three stages.
| Phase | Period | Iran’s instrument | US instrument |
|---|---|---|---|
| Destruction | Late Feb – April | Strait closure, missiles on bases | Strikes on nuclear and missile sites |
| Negotiation | June – mid-August | Transit reopening as a bargaining chip | Sanctions relief, reconstruction funds |
| Contest over administration | Late August – present | Sanctions zone, corridor designation, service denial | Strikes on shadow-fleet tankers |
The 14-point memorandum of understanding the two sides signed on 17 June carried a 60-day negotiating window. That window expired on 17 August, and no progress has been confirmed since. On 26 August came word that Iran and Oman had established a temporary corridor, but Iran’s foreign ministry attached a condition: the strait would not reopen to US vessels until Washington met its obligations under the June memorandum. No one declared the talks over. The instruments changed instead.
Ten days in September — the targets moved to ships
On 1 September, US Central Command announced strikes on numerous IRGC targets in southern Iran. The following day Iran fired missiles and drones at US bases in Jordan, Bahrain, Kuwait and Iraq. Up to that point, this was the exchange that had repeated all summer. What came next was different.
On the night of 8 September, Central Command said it had destroyed five Iranian oil tankers. The stated reason was that the IRGC had targeted a US Navy warship with ballistic missiles twice in two days. Secretary of State Marco Rubio’s formulation summarizes the policy: “Iran continues to try to hit US naval ships, and for every time they do that or try to do that, they’re going to lose tankers.” Iran claimed it had attacked ten vessels near the Strait of Hormuz. Among ships with confirmed damage were the products tanker Hercules Star off Dubai (one seafarer killed, one missing), the New Andros in Iraqi waters, which caught fire after a drone strike while carrying two million barrels of crude (all 22 crew unharmed), and an LNG vessel damaged at the Emirati port of Khor Fakkan.
Separating the confirmed from the asserted: confirmed — Central Command’s announcement and footage of the five tanker strikes, Jordan’s interception statement (18 of 20 missiles downed, no casualties), and individual vessel damage reported by operators and maritime security firms. Asserted — the IRGC’s tally of “ten ships attacked” and Iranian state media’s civilian casualty reports. The latter have not been independently verified and the figures may yet be revised.
Hormuz strait control — this is an administrative act, not a blockade
Read Mohebbi’s statement again and the vocabulary is more administrative than military. Designate a zone, compile a list, refuse to provide services. The language of force is attached only to the strait itself. For the wider waters beyond it, he promised disadvantage rather than violence. The new corridor that Mohsen Rezaei, secretary of the Supreme National Security Council, previewed on 6 September came with the same framing: it lies “in Iranian and Omani waters,” and “Iran will have management.”
Why this method? A principle I learned in uniform has explanatory power here. The weaker side avoids a decisive engagement where its opponent is strong and drags the problem into a domain where the opponent is structurally poorly equipped to respond. In missile exchanges Iran keeps losing. An exchange ratio in which twenty missiles yield eighteen interceptions, as in the Jordan case, is not a sustainable form of war. Rules and paperwork, by contrast, cannot be intercepted. There is no way to shoot down a notice that port services will be withheld.
There is, I think, a further calculation layered on top. A blockade makes an enemy of the entire world. Passage administration, by contrast, lends the appearance of a party that supplies order. Fees and permits are the language of sovereignty, and the language of sovereignty converts into equity at a negotiating table. That reports mention revenue sharing in the Omani corridor suggests the conversion has already begun.
This strategy does, however, contain a way of shooting oneself in the foot. Iran’s own crude exports use the same waterway. The moment the United States answers tanker for tanker, the side that wants to write the rules is the side that first loses the means to enforce them — its own ships. The 8 September strike near Kharg Island appears to have been aimed precisely at that point.
What $100 oil actually priced in
Brent crossed $100 a barrel on 9 September, the first time since July. The day before it touched $99 and settled in the $97 range; on the 7th, immediately after the weekend attacks on shipping, it sat around $97. Over the same stretch came reports that Houthi forces had targeted Saudi Arabia’s Jazan refinery, a facility of roughly 400,000 barrels per day.
How should these numbers be read? I do not believe the market bet on the strait closing. Had it done so, the move would not have stopped at $100. What the market priced in is that the cost of transiting the strait is rising structurally. War-risk premiums, freight on rerouted voyages, waiting time and the cost of crewing do not come back down easily once they go up, even if a ceasefire arrives. In a piece in June on the gap between oil prices and inventories, I asked when the compressed spring would release. The way it is releasing now is not a supply cut but a repricing of passage.
Read alongside this an analysis of the marine insurance market that argues insurance is a more binding chokepoint than any physical blockade, and the picture sharpens. Iran’s choice of “service denial” as a weapon is no accident. It is the cheapest available way to stop a ship without sinking it.
The indicators of Hormuz strait control disagree with each other
This is where the greatest care is needed in the current phase. Three numbers are circulating about the same strait.
- US Energy Secretary: daily transit volume as of 2 September described as the highest since the war began
- Maritime trade press: roughly 10 commodity vessels a day over the past ten days — the lowest since May
- Preliminary count for 9 September: six ships transiting in 24 hours with their transponders on
All three can be true. The qualifier attached to the third is the key. Ships that switch off their identification systems are not counted. If a sanctions-evading “shadow fleet” handles a substantial share of transits, you get exactly this combination: high volumes measured in barrels alongside a collapse in identifiable vessels. Official statements count barrels; the market counts ships it can verify.
In a phase like this, what a reader needs is not a more precise number but the habit of reading a number’s definition first. The principles I set out for separating verification from one-sided claims in open-source intelligence collection apply directly to this case. As a basis for judgment, I watch war-risk premium rates and rerouted volumes before any announcement of transit barrels. Premiums are hard to dress up politically.
The IAEA referral — thin in effect, durable as record
On the same 9 September, the Board of Governors of the International Atomic Energy Agency referred Iran’s file to the UN Security Council over non-compliance. It is the first such referral in twenty years. According to reports, at least 23 of the 35 board members voted in favour, with Russia, China and Niger opposed. Director General Rafael Grossi described the agency’s lack of information about the facilities and associated nuclear material, and its inability to conduct verification activities there, as a matter of serious proliferation concern.
Yet this referral is unlikely to translate into sanctions. Russia and China hold vetoes at the Security Council. So what is the procedure for? I read it not as a sanctions step but as a record-keeping step. The fact that the agency cannot account for roughly 400 kg of highly enriched uranium is now fixed in the documents of an international body — material that, with further enrichment, the agency assesses could suffice for several weapons. That record changes nothing today. It will be cited as grounds for whatever is done later.
Iran’s UN mission rejected the resolution as a political decision and argued that inspections became impossible because of US and Israeli attacks. There is a kernel of fact in that objection: demanding normal inspections of facilities that have been struck is not a reasonable request. But the objection does not dissolve the problem of not knowing where the material is. I argued in a July piece that changing a leader does not remove a programme. We have now moved to a stage where even that programme’s inventory cannot be verified from outside.
Three paths for the next three months
Hormuz strait control is the variable that will shape the international picture over the coming three months. Closing out the summer phase, I wrote that this war had moved from breaking things to squeezing them (related post). September went a step further: the squeezing hand now writes rules. Three paths follow from there.
Path A — de facto acceptance of the corridor. Oman provides the public face, Iran participates in management, and the route actually functions while Washington tolerates it without formal recognition. Transits recover and oil could settle back into the $90s. This path leaves Iran with a quasi-sovereign stake, however, which means a domestic political bill for the United States.
Path B — tanker for tanker, entrenched. The present state persists for months. Neither side wins decisively, and oil oscillates between roughly $95 and $110 in step with premium rates. I consider this the most likely path. In that case the indicator that matters is not news from the front but reinsurers’ published rates.
Path C — accumulating third-country seafarer deaths. If sailors from countries that are not belligerents keep dying, as in the Hercules Star case, states that have so far stood back get pushed into convoy operations or joint responses. Multinational escorting widens the surface of contact and opens room for expanded strikes inside Iran. I rate the probability low, but it is a path that is hard to reverse once switched on.
The limits of this analysis
What I treated as fact and what I held back
What I have written here as confirmed fact comes from Central Command’s official announcements, the Jordanian government’s interception statement, the IAEA Board’s vote, individual vessel damage reported by operators and maritime security firms, and oil prices as traded. The IRGC’s attack tallies and Iranian state media’s civilian casualty figures are marked as claims. Both sides have clear incentives to adjust numbers to fit their narrative.
And the central argument of this piece — the move “from blockade to administration” — is my judgment, not a fact. Whether Iran’s turn to rules is a strategic shift or a temporary patch applied after its physical instruments ran down will be settled by whether enforcement follows in the coming weeks. If a sanctions list is actually published and specific vessels are actually refused, the former gains weight. If announcements repeat with no enforcement, it is the latter. I will keep watching that point.
Frequently Asked Questions (FAQ)
In the current phase, I rate it low. A full closure would also block Iran’s own crude export route and turn its largest customers, China included, into adversaries. The direction of the September measures is the opposite: not to block passage but to set the terms of passage. That calculation could change, however, in the event of large-scale strikes on the Iranian mainland.
On the question of Hormuz strait control authority, the law of the sea does not recognize a coastal state’s power to impose transit conditions on waters beyond its own. But what Iran’s measure appears to target is practical friction rather than legal validity. Refusing port access, insurance, bunkering and water imposes real costs on operators regardless of legal justification. That is why enforcement cases matter more than legal effect here.
I do not think naming a price target is appropriate. What does seem reasonably clear is that the variable currently moving prices is transit cost rather than supply volume. So instead of forecasting a dollar figure, I watch war-risk premium rates and rerouted volumes first. If those two stabilize, prices have room to follow them down. Investment decisions remain each reader’s own responsibility.
Security Council resolutions are subject to the permanent members’ vetoes, and Russia and China voted against at this Board meeting. Neither currently has an incentive to change position at the Council. The referral therefore reads less as an enforceable measure than as a way of fixing Iran’s non-compliance in the record of an international body.
📚 References
- Council on Foreign Relations — Confrontation Between the United States and Iran (Global Conflict Tracker)
- House of Commons Library — US-Iran ceasefire and nuclear talks in 2026
- Al Jazeera — IAEA board resolves to report Iran to Security Council (9 Sep 2026)
- Al-Monitor — Iran’s IRGC set to declare new ‘sanctions zone’ beyond Hormuz
- gCaptain — Iran says to announce new restricted zone in the Gulf
- Defense News — Iran and US hit tankers in biggest wave of attacks on shipping since war began
- CNBC — Brent crude tops $100 as US-Iran strikes stoke supply worries