US-Iran tensions are reshaping the global Brent oil curve

"The return to backwardation signals that the market expects crude availability to remain constrained in the weeks ahead," Saxo Bank head of commodity strategy Ole Hansen said.

The structure contrasts with that in early July, when prompt Brent traded below later contracts, a more common structure known as contango and typically associated with ample near-term supplies. Recovering exports through the strait then eased supply concerns.

"For the moment, this is largely a paper move, with investors likely pouring back into the market following the latest escalation," said Neil Crosby, head of research at Sparta Commodities.