The U.S.-Iran deal ending months of fighting and reopening the Strait of Hormuz will prompt a collective sigh of relief from energy exporters and importers alike. But the fragile calm may not prevent future flare-ups, casting doubt over how quickly – or fully – tanker traffic through the vital waterway can return to normal.

The trickle of tankers exiting the Strait of Hormuz has gathered pace in recent weeks, as traders adopt stealth measures to make the crossing. While this is freeing some of the vast oil inventories trapped in the Gulf, it does not signal a slow return to normalcy. Instead, it previews the opaque, fragmented energy market the Iran war is set ​to leave in its wake.