By Weilun Soon and Alex Longley.
Non-Iranian oil flows through the Strait of Hormuz have surged by about 50% so far this month, as more Persian Gulf producers find ways of transiting the waterway despite continued tension between Washington and Tehran.
At least 1.8 million barrels a day transited out of the Persian Gulf in the first 10 days of June, up from 1.2 million a day in May, according to Vortexa. Those figures tend to be revised upward as more tankers are observed, aided by satellite-image analysis.
Iran’s shipments through the corridor, by contrast, have plummeted, as a US-imposed blockade continues to hold back tankers. No Iranian oil transited during the period, Vortexa data showed.
The strait has been a focus of the war since US and Israeli strikes began in late February, prompting Iran to take control of the corridor. That grip has begun to falter as so-called “dark” transits rise — but flows are still a fraction of pre-war levels of about 20 million barrels of crude and products a day.
“Transiting through the strait without AIS signals has become the new norm,” said Xavier Tang, a senior market analyst at Vortexa, referring to the transponders that vessels use to transmit locations and other identifying information during a voyage.
The market has begun to count on increased flows. When Tehran’s Persian Gulf Strait Authority declared the waterway closed on Thursday, Brent futures were little changed — a far cry from the outset of the war, when a 13% jump in prices greeted Iran’s first shutdown of Hormuz.
That may partly reflect what President Donald Trump has referred to as a secret project to help about 100 million barrels of oil to clear Hormuz since last month. The figure, if accurate, would equate to at least 2.4 million barrels a day since the start of May.
The large volume of escaping Gulf oil has combined with a collapse in Chinese crude imports and releases of emergency reserves to bring futures prices down by almost a third from their highs at the peak of the conflict.
So far, the renewed hostilities between the US and Iran haven’t ensnared regional energy assets, though traders will focus on whether ships can keep escaping in the face of Iran’s latest statement on a Hormuz closure.
The US has also ramped up its own attacks on ships it says are attempting to enter Iranian ports, hobbling Tehran’s flows. So far this week, Central Command has said that it disabled two vessels in the Gulf of Oman for attempting to breach a blockade that has been in place since mid-April, while a third ship suffered a fire in its engine room on Thursday.
© 2026 Bloomberg.