OPEC+ keen to keep U.S. shale in check as oil prices rally

LONDON (Reuters) - When OPEC, Russia and their allies agreed in April to slash oil production, little did they expect that their initiative to prop up collapsing prices would be helped by a swift drop in U.S. output.Now that crude has rallied on the back of those cuts from below $20 a barrel to $40 or more, the group known as OPEC+ faces a fresh challenge: stopping U.S. shale production delivering another surprise by recovering equally quickly."The plan is to stick to prices of $40-$50 per..