The Cargo Changes Ships

Both governments claiming the Strait of Hormuz spent late summer escalating their paperwork over it. The waterway's principal users answered with something neither had accounted for. Gulf oil now crosses in relays that transfer cargo outside the strait, and volume has roughly doubled since mid-July while the number of ships crossing has fallen to single figures on some days.

On Sunday evening the secretary of Iran's Supreme National Security Council went on state television and announced a restricted zone. It would begin, he said, where the American blockade of Iranian ports starts, and run from there into the Gulf. Any vessel entering it would be added to a sanctions list. He gave no coordinates. He named no legal mechanism, no enforcing body and no penalty beyond the list itself. In the same interview he said the maps of a new international corridor lying in Iranian and Omani waters, under Iranian management, had been agreed and would be signed within days. Muscat has published nothing. Its foreign minister told Gulf counterparts in June that future arrangements for the strait would not carry transit fees.

Washington has been assembling a file of its own. Tehran now runs three institutions over the waterway: an authority that issues permits and publishes routing schemes, a marine insurance company and a safe-passage services body. The US Treasury designated the first in late May and the other two at the end of July. Its August guidance reaches past money. A shipowner who merely answers Tehran's request for information about a transit, accepting nothing and paying nothing, is told that the reply alone carries sanctions exposure. Service providers are instructed to ask their counterparties who they coordinated with to get through.

Two weeks earlier the Iranian authority had published its own list, forty-five vessels accused of breaching its transit rules and threatened with detention, confiscation or fines. The largest single owner on it is Abu Dhabi's state shipping arm, with eight ships. There is Saudi tonnage too. One clause matters more than the rest: any vessel that transfers cargo with a listed ship joins the list.

That clause is aimed at what the Gulf actually built. Since mid-July, oil moving through Hormuz has climbed from roughly four million barrels a day to as much as eight, and it has done so while crossings fell. Ten commodity ships a day over the past ten days, the lowest count since May. Six on the second of September. The two numbers reconcile through relay. National oil companies now put their own hulls into the strait, absorb the transit risk themselves and hand the cargo to another ship on the far side. Abu Dhabi ran it first at scale. Kuwait and Qatar followed. One analyst who watches the traffic puts it plainly, that shuttling has stopped looking like an emergency workaround and started looking like the way Gulf crude is sold.

Something worth holding open. Most transits through the strait now run dark, and the firms counting them say so. Of 568 crossings in the month to late August, 332 could not be assigned to any route at all. Seven used the pre-war internationally recognised lane. That gap is real, and what it means is genuinely contested. Vessels running with transponders off may be dodging Tehran's registry or Washington's compliance questions, and some are probably just hiding a commercial handover from competitors. The people with the best data say they cannot tell.

What is not contested is the direction. A waterway acquires two rival administrations and its biggest customers respond by designing a way to touch it as briefly as possible. Both capitals are still arguing about the rules of a road that the traffic is engineering itself off.