Two days after the Houthi movement declared a naval blockade against Saudi Arabia, the Red Sea corridor has fractured into two opposing patterns of vessel movement, according to maritime intelligence firm Windward. Commercial tankers are reversing course away from the Bab al-Mandeb Strait, while at least one sanctioned Iranian vessel has pushed into the same waters for the first time in its tracked history.
Commercial Tonnage Retreats
Windward reports that five tankers heading toward Bab al-Mandeb reversed course as blockade threats intensified. According to the firm, four of these vessels were carrying Saudi-origin crude, gasoil, and naphtha cargoes, totaling an estimated 3.84 million barrels based on data from Vortexa. Four turned back within the Red Sea itself, while one reversed course further out in the Gulf of Aden.
The diversions affected shipments from both of Saudi Arabia’s western export terminals, Yanbu and Jizan, Windward notes. Among the vessels involved was the VLCC Xin Long Yang, a Singapore-flagged, 333-meter crude tanker managed by Cosco Shipping Energy, which departed Yanbu southbound before reversing course while still declaring Qinzhou, China as its destination, according to Windward’s tracking data.
Not all operators are avoiding the area. Windward reports that three Saudi-linked VLCCs continued crossing or approaching the strait despite the threat, while three Saudi-flagged VLCCs went dark on July 20. The firm notes that full avoidance via the Cape of Good Hope roughly doubles voyage length and adds an estimated $2-2.5 million in cost per transit, a factor likely weighed by owners deciding whether to press on.
Windward’s aggregate tracking shows 26 vessels crossing into the Red Sea against 17 outbound on July 20, with inbound crossings falling from a mid-July peak of roughly 45 to below 15 within days.
A Sanctioned Vessel Moves the Opposite Way
Against this outbound flow, an OFAC-sanctioned, Iranian-flagged container vessel entered Yemen’s exclusive economic zone and crossed Bab al-Mandeb on July 21, according to Windward. The firm states this marks the first Red Sea activity recorded anywhere in the vessel’s available tracking history, occurring one day after the blockade announcement and breaking a six-month pattern confined to the Persian Gulf-China corridor.
Windward reports the vessel carries active OFAC designations under the Iran and NPWMD sanctions programs, along with a high smuggling risk score and a behavioral record including nine AIS dark gaps, seven loitering instances, and a past identity-manipulation event. The firm adds that prior reporting has linked the vessel to suspected rocket-fuel-material cargoes. Windward assesses the transit as a potential indicator of Iran-Houthi coordination, though it stops short of confirming the nature of any such arrangement.
Pressure From the Strait of Hormuz
Windward links the Red Sea shift to conditions in the Strait of Hormuz, where the southern corridor has reportedly slowed to a near-standstill under a standing IRGC closure declaration. The firm logged 11 inbound and 4 outbound Hormuz transits on July 20, all routed through the northern corridor, with several vessels running dark.
According to Windward, Iranian forces struck two Greek-operated tankers near Kumzar, Oman on July 20, followed by a Kuwaiti state-owned tanker near Limah overnight — the third vessel struck in the southern corridor within a single day. All three were reportedly transiting with AIS switched off at the time of attack. Windward also reports that 21 tankers were assessed congregating at Iran’s Kuh-e-Mubarak anchorage, with nine running dark and seven under OFAC designation.
Does This Matter to You?
According to Windward’s tracking data, the diverging patterns in the Red Sea and Strait of Hormuz carry direct implications for anyone monitoring vessel routing, cargo delivery timelines, or war-risk exposure in the region. The reported reversal of tankers carrying Saudi crude, gasoil, and naphtha suggests potential delays and rerouting costs for cargoes originating from Yanbu and Jizan, with Windward noting that Cape of Good Hope diversions add substantial time and cost per voyage.
The presence of a sanctioned Iranian vessel making its first-ever Bab al-Mandeb crossing, as reported by Windward, may signal shifting risk dynamics in the corridor that could affect insurance considerations and compliance screening for vessels operating nearby. The wider disruption at Hormuz, including dark transits and vessel strikes reported by Windward, further underscores the volatility affecting both strait systems simultaneously. Windward states it will continue monitoring whether the Bab al-Mandeb traffic gap widens and where the affected Saudi-flagged VLCCs resurface.
Gulf Bunkering does not provide operational or security guidance. This article is for informational purposes only. Operators should consult flag state authorities, P&I clubs, and relevant advisories for decisions relating to transit planning.
Sources: Windward
