Middle Eastern crude markets declined after the agreement between the United States and Iran to reopen the Strait of Hormuz boosted optimism about increased flows from the oil-rich region. The futures price curve for benchmark crudes, such as Dubai and Murban, entered contango for the first time since the start of the war. This market pattern, in which near-term contracts trade at a discount to longer-term contracts, indicates a decrease in concerns about supply shortages.In addition to expectations of increased barrels, the Abu Dhabi National Oil Company (ADNOC) launched a tender earlier this week to sell crude oil originating within the Arabian Gulf, for loading in June or July.In theory, resuming flows through the Strait of Hormuz would mean an increase in the volume of barrels, which would put downward pressure on prices. Millions of barrels are also stored on ships within the Arabian Gulf, which would add to any increase in production from producers in the region.However, ship owners and traders are still awaiting clarity on what the agreement will practically mean for reopening the Strait of Hormuz, creating uncertainty about how quickly flows will return to the market. But even before the agreement, increasing amounts of oil were trickling through the waterway, with one industry source estimating the flow at 4 million barrels per day.The spread between the July and August contracts for Dubai's benchmark crude was 6 cents per barrel in contango on Tuesday. This is the weakest level since late January, compared to an intraday peak of more than $13 in the inverse structure known as backwardation in March. The near-term spread for Murban, Abu Dhabi's main crude, was 21 cents in contango on Tuesday, after peaking at more than $30 in backwardation in March.