The US military has secretly coordinated the transfer of an estimated 90 million barrels of Gulf oil since May, adopting Iran’s own sanctions-evasion tactics to covertly move the oil, a recent Reuters investigation revealed.

Two specific locations where the oil transfers take place were identified by 11 people familiar with the operation, in which at least 92 ships have been involved, according to shipping data and satellite imagery.

The ship-to-ship transfer operations, a shuttling technique long used by Iran to skirt sanctions, are fully controlled by the US military, said eight of the sources, including someone involved in the transfers.

Tankers must sail to a meeting point before they reach the strait, then stagger their departures so they are around 3,000 to 4,000 metres apart. Their transponders are off, and their lights are dimmed, sources say.