Oil still flows through blocked Strait of Hormuz as tankers go dark

As Iran has offered to open the Strait of Hormuz for seven days and enter negotiations with the United States if Washington halts hostile actions, analysts say a growing number of tankers have been slipping through the strait undetected.

Despite Iran's months-long blockade of the Strait of Hormuz, oil prices have remained relatively stable because a growing number of tankers are transiting the strait with their automatic identification systems, or AIS, switched off, Nikkei reported Monday.

Data from European research firm Kpler show that crude oil flows through the Strait of Hormuz averaged 9.36 million barrels per day this month, up 3.56 million barrels from August. That is the highest volume recorded since the United States launched airstrikes on Iran in late February. Before the conflict, roughly 15 million barrels of crude passed through the strait daily; the current figure represents a recovery to about 60 percent of that level.

Analysts say the increase has been driven in part by tankers transiting the strait covertly with their AIS transponders turned off. The International Maritime Organization requires vessels on international routes to keep their AIS active and broadcast their location. Ships may switch off the system as an emergency measure when their safety is threatened.

Running dark makes it harder for Iran to track a vessel's position, reducing the risk that it will be targeted by a drone strike or seized as it passes through the strait.

Oil prices have consequently held steadier than expected, according to market analysts. West Texas Intermediate futures traded in the $91–$95 per barrel range on Friday, about 20 percent below the post-war peak of around $119 per barrel.

Saudi Arabia has also increased crude shipments through the Strait of Hormuz after Houthi attacks made the Red Sea route increasingly dangerous, further boosting traffic through the waterway. When Iran first closed the strait, Saudi Arabia shifted more of its exports through the East-West Pipeline to the port of Yanbu and then onward via the Red Sea. But after the pipeline was damaged in a drone strike and the Houthis blockaded the Red Sea, the kingdom has been routing more crude back through the Strait of Hormuz.

According to British research firm Argus Media, Saudi state oil company Aramco has launched a spot tender to deliver crude cargoes for the September–November loading period via transshipment in Omani waters — a route that requires passage through the Strait of Hormuz.

Iraq, which relied on the Strait of Hormuz for more than 90 percent of its crude exports before the war, is also now making every effort to push tankers through the strait, Nikkei reported.