Saudi Arabia and Russia have promised they will lead OPEC and other big oil producers in a deal this week to boost output and lower prices. What if it isn’t enough? International oil prices have eased off 3½ year highs in recent weeks, as Riyadh and Moscow publicly trade views about how to loosen up a two-year pact they struck to throttle back production. Worry that trade tensions could sap economic growth—and oil demand—have also cooled prices. Those fears aside, oil demand has actually been growing, and a series of big, unexpected supply outages is making the calculations over how much OPEC should boost output particularly tricky. Iran poses a further risk to an accord after it staked out its opposition this week to any increase. U.S. sanctions against Iran are expected to make many of that country’s barrels unsaleable. All that could test the ability of Saudi Arabia, […]