Two Closed Corridors: Hormuz and Bab el-Mandeb Both Effectively Shut to Tanker Traffic

At a Glance

• Hormuz recorded 6 transits on July 27, all via the northern corridor, with zero tanker crossings in either direction.
• Bab el-Mandeb crossings fell 22% since the July 20 Houthi blockade declaration, with tanker transits down 39% and Saudi-linked crossings down 46%.
• Lloyd’s market insurers began excluding Saudi-linked vessels from war risk cover on July 24, driving the sharpest decline in tanker transits.
• Windward assessed 102 potential blockade-breaker vessels on July 27, including 5 Tier 1 candidates within approximately 65 nautical miles of the blockade line.
• Two vessels are assessed as having already crossed the blockade line undetected while operating dark.
• Yanbu King Fahd Industrial Port is operating entirely AIS-dark, with 22 vessels detected across two July 28 passes and 12 actively loading.
• Windward identified 158 vessels across five parameters as potentially exposed to Houthi targeting, including two Bahri VLCCs currently inside Yemeni waters.
• Three China-linked VLCCs transited Bab al-Mandeb in two days despite the Houthi blockade, suggesting Chinese oil cargoes loaded from Yanbu have secured an exemption.

Operational Overview

Both major Gulf corridors are effectively closed to normal commercial tanker traffic, for different reasons on each side. Hormuz recorded zero tanker crossings on July 27, with all six transits routing through the IRGC-controlled northern corridor. Bab el-Mandeb crossings have fallen 22% since the July 20 Houthi blockade declaration, with tanker transits down 39% and Saudi-linked crossings down 46%.

The mechanisms differ. Hormuz is closed via IRGC enforcement, sustained IRGC high-speed craft presence in the southern strait, and the northern corridor bottleneck. Bab el-Mandeb is closing via a Houthi blockade backed by a Lloyd’s market insurance withdrawal from Saudi-linked vessels, which took effect on July 24 and is assessed as the primary driver of the sharpest tanker decline.

Iranian and Saudi crude are both still moving, but under altered conditions. On the Iranian side, 102 potential blockade-breaker vessels are lined up across three tiers, with five Tier 1 candidates within approximately 65 nautical miles of the blockade line and two vessels assessed as having already crossed undetected. On the Saudi side, Yanbu King Fahd Industrial Port is operating entirely dark with continuous loading throughput, and three China-linked VLCCs have transited Bab el-Mandeb loaded from Yanbu, suggesting Chinese oil cargoes have secured an exemption from the Houthi blockade.

Windward assesses the operational risk environment across the Strait of Hormuz, Gulf of Oman, northern Arabian Gulf, Red Sea, and Bab el-Mandeb as Critical, with both major Gulf corridors effectively closed to normal commercial tanker traffic, active kinetic threats on both fronts, and enforcement and evasion patterns compounding across the wider region.

Hormuz Effectively Closed to Tanker Traffic

July 27 recorded 6 total transits, 3 inbound and 3 outbound, all via the northern corridor with zero tanker crossings in either direction. The inbound group comprised a Marshall Islands-flagged bulk carrier and an Iran-flagged cargo vessel transmitting AIS, alongside one dark contact. The outbound group comprised a Hong Kong-flagged cargo vessel and a Gambia-flagged cargo vessel transmitting AIS, alongside one dark contact.

EO imagery collected over the Strait on July 27 at 09:47 UTC confirmed a swarm of 6 IRGC high-speed craft holding position in the southern strait, a dark laden bulk carrier anchored inside an active transiting corridor, a dark tug of approximately 40 meters and a dark general cargo vessel of approximately 87 meters both moving outbound, and one AIS-matched inbound general cargo vessel of 72 meters with a high-speed craft alongside.

A separate EO collection over the western corridor at 06:48 UTC identified a dark LPG tanker in ballast assessed as stationary across at least two consecutive collection cycles, and a dark bulk carrier assessed as transiting inbound toward the Iran EEZ or the Iranian-controlled northern corridor.

An earlier collection on July 27 at 03:49 UTC over the Ras Al Khaimah approach corridor identified two dark vessels transiting inbound to the Arabian Gulf, made up of a dark general cargo vessel of approximately 160 meters and a dark VLCC-class tanker of approximately 333 meters.

The exclusive use of the northern corridor across all transits, the complete absence of tanker crossings, and continued IRGC high-speed craft presence in the southern strait confirm that the Strait remains effectively closed to commercial tanker traffic.

102 Potential Blockade Breakers Line Up Against the Line

Windward assessed 102 potential blockade-breaker vessels on July 27 across three tiers. Five vessels are assessed as Tier 1, meaning imminent, within approximately 65 nautical miles of the blockade line with confirmed laden intent toward a genuine trans-oceanic destination.

A Norway-flagged OFAC Iran-sanctioned tanker of 110 meters was promoted to Tier 1 after Vortexa confirmed its declared Djibouti destination masks a genuine diesel cargo of approximately 63,900 barrels actually bound for Port Klang, Malaysia, approximately 62 nautical miles from the line. A Guinea-flagged crude tanker carrying approximately 443,000 barrels of Iranian heavy crude declared for Karachi but Vortexa-confirmed for Longkou, China, approximately 58 nautical miles from the line, is drifting at near-zero speed in floating storage posture.

An Iran-flagged bulk carrier approximately 51 nautical miles from the line, unmoved for over a week, with erratic AIS behavior consistent with position manipulation, briefly crossed the blockade line in mid-July and has returned to the same threshold position. An Iran-flagged VLCC of approximately 320 meters, dark for 6 days, last confirmed approximately 62 nautical miles from the line, is carrying approximately 2.01 million barrels of Iranian heavy crude for Dongjiakou, China, the largest single cargo on the watch list. A fifth vessel, approximately 63 nautical miles from the line, is Vortexa-confirmed as carrying an intra-Iran cargo to Chabahar, not an active blockade threat despite proximity.

Two vessels are assessed as having already crossed the blockade line undetected. A Comoros-flagged tanker and a Curacao-flagged tanker both loaded genuine long-haul Iran-origin cargo for Taiwan and China respectively approximately one week ago and have been AIS-dark since departure, both assessed as having crossed the line without detection.

Five Tier 2 vessels remain between 65 and 250 nautical miles from the line with credible outbound intent, including a Marshall Islands-flagged VLCC of 330 meters bound for Jask, Oman, and a Palau-flagged crude tanker of 106,000 DWT bound for Sohar, Oman. Three vessels previously flagged as candidates, an Iran-flagged OFAC-sanctioned tanker, a Comoros-flagged tanker, and a Marshall Islands-flagged tanker, were confirmed by Vortexa as short intra-Gulf moves to Fujairah or Sharjah and removed from the list.

The Houthi Blockade Intensifies Across the Red Sea

The Houthi resumption continues to intensify. The Houthi blockade declaration against Saudi-linked shipping, effective July 20, has triggered a measurable and accelerating commercial response across the Red Sea corridor.

Bab el-Mandeb crossings fell 22% since the July 20 blockade declaration, from approximately 47.8 vessels per day before to approximately 37.2 per day after. Tanker transits fell 39% and Saudi-linked crossings fell 46%, the steepest decline of any tracked group. The tanker decline sharpened specifically after war risk insurance reporting on July 24, falling to approximately 7.5 tankers per day against approximately 12 per day immediately after the blockade declaration. Crude tankers slow-speeding or reversing near the Gulf of Aden exit are up 138% since July 19, now 13 vessels, assessed as ships holding position rather than committing to the corridor.

10 vessels departed Yanbu this past week carrying Saudi crude, products, and LPG to China, India, Pakistan, and Japan, all via Bab el-Mandeb.

Windward Early Detection data shows oil and chemical tankers conducting dark activity in the Saudi Red Sea rising 144% during July 19 to 26, assessed as a security-driven response linked to vessels port-calling at Saudi Red Sea ports and then going dark.

Windward identified 158 vessels across five parameters potentially exposed to Houthi targeting, including 4 Saudi-flagged and 11 Saudi-owned vessels transmitting in the Red Sea and Gulf of Aden, 9 Bahri VLCCs and bulk carriers transiting the Arabian Sea westbound, 11 vessels on Vortexa-tracked Red Sea flows through the corridor, and 123 vessels that called at Saudi Red Sea ports between July 23 and 25 and then went dark between July 23 and 26. Two Bahri VLCCs currently show AIS positions inside Yemeni waters, directly inside the Houthi engagement zone.

Three Chinese-owned VLCCs transited Bab el-Mandeb without incident on July 23 to 24, consistent with the Houthis’ established carve-out for Chinese and Russian-linked vessels. A Hong Kong-flagged VLCC carrying approximately 2 million barrels of crude loaded at Yanbu transited with AIS active toward Ningbo, China. This is the third China-linked VLCC to transit the area in two days despite the blockade on Saudi-origin cargoes, suggesting Chinese oil cargoes loaded from Yanbu have secured an exemption.

Lloyd’s Withdraws War Risk Cover From Saudi-Linked Vessels

Lloyd’s market insurers are excluding ships with Saudi links from war risk cover, including vessels that merely called at a Saudi port in the past, pushing trade back toward the pre-2024 pattern of seeking permission from the HOCC before transiting. The insurance withdrawal took effect from July 24 and is assessed as the primary driver of the sharpest decline in tanker transits through Bab el-Mandeb, which fell to approximately 7.5 per day after the story broke, from approximately 12 per day immediately prior.

Yanbu Operates Fully Dark With Continuous Loading Throughput

EO imagery collected over King Fahd Industrial Port at Yanbu on July 28 across two passes, at 05:09 UTC and a clearer 07:39 UTC collection, confirmed that all vessels at berth and in the waiting area are operating dark with no AIS transmission, an ongoing trend assessed as safety-driven to avoid association with Saudi Arabia and Houthi targeting.

The 07:39 UTC collection, taken under clearer conditions than the earlier pass, identified 22 vessels in total. Twelve vessels were assessed as actively loading across berths, made up of 7 tankers ranging from approximately 144 to 339 meters and 5 bulk carriers ranging from approximately 180 to 229 meters. Ten dark tankers were stationary in the waiting area. Two tanker departures were confirmed visible in this collection, corroborating an active loading cycle. One dark tanker of approximately 339 meters was newly detected at berth in the 07:39 UTC pass, not visible in the earlier collection due to cloud cover. Three tankers in the waiting area were new arrivals. At least one tanker departed on July 27, with two departures confirmed the prior day, confirming continuous throughput.

The transition from AIS-active to entirely AIS-dark operations reflects vessels actively turning off AIS when approaching the port to shield themselves from the Houthi hit list targeting Saudi-related vessels.

Kharg Island LPG Terminal Sees Fresh Arrival, Frequency Declining

EO imagery collected over Kharg Island on July 27 at 08:08 UTC showed a dark tanker of approximately 185 meters newly arrived at the LPG terminal, not present in the prior collection. The eastern and western terminals were confirmed empty. The eastern waiting area held only 2 dark stationary tankers, including a laden vessel of approximately 249 meters assessed as present since July 12, and a ballast vessel of approximately 180 meters assessed as present since May 14. The frequency of vessel arrivals at the LPG terminal is decreasing.

Outlook

Two Gulf corridors are now effectively closed to normal commercial tanker traffic simultaneously. Hormuz is closed via IRGC enforcement and the northern-corridor bottleneck. Bab el-Mandeb is closing via a Houthi blockade backed by the Lloyd’s war risk insurance withdrawal from Saudi-linked vessels. Both are producing the same operational outcome, with tanker crossings collapsing, dark activity surging, and evasion tradecraft spreading across the wider fleet.

Iranian and Saudi crude are both still moving under altered conditions. On the Iranian side, 102 potential blockade-breaker candidates are queued up against the line, with two already assessed to have crossed undetected. On the Saudi side, Yanbu is operating fully dark with continuous loading throughput, and China-linked tonnage has secured an exemption from the Houthi blockade that is now visibly moving Yanbu-loaded crude eastbound through Bab el-Mandeb.

Windward assesses the operational risk environment across the Strait of Hormuz, Gulf of Oman, northern Arabian Gulf, Red Sea, and Bab el-Mandeb as Critical, with both major corridors effectively closed to normal commercial tanker traffic, active kinetic threats on both fronts, structurally elevated dark activity across the region, and Chinese-linked tonnage now visibly operating under differential rules on both fronts.