Is Iran Losing Its Grip on Strait of Hormuz Traffic?

Iran has demanded that all Strait of Hormuz transits use the northern corridor through its territorial waters. Rising volumes of Saudi, Iraqi, and Kuwaiti crude, along with UAE volumes that cannot reach Fujairah by pipeline, are instead moving through the southern corridor, which remains under USCENTCOM air defense and naval support.

Windward MIOC assesses that Iran is less able to constrain southern-corridor traffic than it was in mid-summer, as rising crude flows continue despite the threat to individual vessels.

The AIS Picture Is Misleading

Windward recorded 55 AIS-visible transits from 16 to 23 September, about 94% below pre-war traffic of roughly 910 a week. That count combines AIS detections with at least one satellite imagery pass per day, meaning the true number of transits is almost certainly higher.

Tankers are sailing with AIS switched off, as permitted under maritime conventions when a vessel’s safety or security is at risk.

The Tanker Shuttle

Exports out of the Arabian Gulf now rely heavily on a “tanker shuttle”. Tankers run through the Strait with AIS off, discharge their cargo via ship-to-ship transfer in the Gulf of Oman, then return inside the Gulf. 

With few VLCCs willing to enter the Gulf, exporters are maximizing the volume carried on each crossing, then splitting those cargoes via ship-to-ship transfer onto Suezmaxes in the Gulf of Oman for onward delivery. This reduces the number of vessels that need to make the higher-risk Strait transit.

Tankers are exiting the Gulf in convoys. Between 20 and 22 September, MIOC satellite detections and Vortexa cargo data show 26.72 million barrels of crude exited through the Strait.

Roughly two-thirds of that volume was subsequently moved through ship-to-ship transfers. Spread across those three days, the flow was equivalent to about 8.9 million bpd, although convoy days represent peaks rather than a sustained export rate. For comparison, Vortexa puts Saudi Gulf loadings across 1–27 September at 105.6 million barrels, or 3.9 million bpd.

Saudi Arabia: What AIS Shows Versus What Is Moving

Saudi tankers are still loading crude at Ras Tanura and Juaymah. Most are doing so with their AIS switched off.

Between January 10 and 16, 35 crude tankers called at the two terminals with AIS on. By September 10–16, that number had fallen to just 2. Vortexa’s cargo data, which does not rely on AIS, shows that loadings over the same periods fell from 52 to 16 per week.

Actual loadings are down, but AIS-visible tanker activity has fallen far more sharply. The gap indicates that much of the apparent collapse in tanker traffic reflects vessels switching off AIS rather than crude movements stopping.

The last visible surge came between 1 and 10 July, as the Memorandum of Understanding period closed. Eight crude tankers left Ras Tanura and Juaymah in that window, declaring voyages to China, South Korea, Duqm, and Fujairah. Seven were VLCCs, six of them operated by Bahri, Saudi Arabia’s national shipping company.

After 10 July, the crude tankers still transmitting AIS were mostly smaller vessels moving between Saudi ports, plus a single VLCC, which called at Juaymah on 15 and 16 August. Across all Saudi Gulf ports, visible crude tanker calls fell from 17 in July to 5 in August and 4 in September, with no VLCC calls at all in September.

Vortexa’s cargo data shows the loadings continued. Crude tanker loads at Saudi Middle East Gulf ports rose from 8 in June to 19 in August and 55 in September (per Vortexa). Fifty of the September loads were VLCCs, including 21 operated by Bahri and 14 by Sinokor, the South Korean shipping group. Almost all loaded with AIS off. We assess that Saudi crude is moving through the Strait on AIS-dark tankers.

Why Saudi Crude Is Back in the Arabian Gulf

With East-West pipeline flow reduced after the Petroline attack, less Saudi crude can reach the Red Sea, and Saudi Arabia has shifted exports back to its Gulf terminals. Vortexa puts Saudi Gulf loadings at 3,911 kbpd for 1 to 27 September, more than four times August’s 933 kbpd and 39% below January’s pre-war 6,385 kbpd.

Even so, Gulf loadings remain well below pre-war levels. Middle East Gulf crude exports have recovered sharply since August, but VLCC availability remains constrained. As the East-West pipeline recovers, Saudi Arabia is likely to shift more crude back to Yanbu while tensions persist in the Strait of Hormuz.

Where the Crude Is Going

Vortexa tracks 33 September cargoes from Saudi Gulf terminals, about 58 million barrels, bound for China and India, more than three times August’s 17 million barrels. Some of the 33 were shuttled via ship-to-ship transfer off Fujairah and Oman, so the vessel that loaded the crude is not always the vessel delivering it, and the final destination can change. 

Windward Maritime AI™ platform data identifies declared destinations for 13 of the 33 cargoes. Eight are broadcasting destinations in China, with ETAs between 4 and 15 October. Five are broadcasting destinations in India, and most had already arrived at Vadinar and Sikka as of 28 September.

Strikes Have Not Stopped the Flow

Iran retains the ability to strike individual vessels. AL MARYAH (IMO 9393682) and LR STEPHANIE (IMO 9282625) were hit between 20 and 22 September, the same three-day period in which 26.72 million barrels of crude exited through the Strait. Laden Gulf exits continued despite the strikes. MIOC assesses that, under current conditions, such attacks are more likely to cause short-lived disruptions than a sustained reduction in exports.

The recovery in crude flows is real, but remains vulnerable to further escalation.

This assessment reflects available data at time of collection (AIS reporting, cargo-flow tagging, or open-source signals) and may not represent a complete or constant-area picture. Figures, positions, and identifications are analyst-assessed from the cited sources and should be treated as indicative, not confirmed, pending independent verification.

Analysis by Zane Amundsen, MIOC Middle East Desk Lead, Windward. Reviewed by Matthew Mueller, MIOC U.S. Team Lead and Michelle Wiese Bockmann, MIOC Senior Maritime Intelligence Analyst, Windward