OnlineTrump blames Opec for high oil pricesSome Opec members responded to the accusation via TwitterFILE PHOTO: U.S. President Donald Trump delivers remarks during an 'Unleashing American Energy' event at the Department of Energy in Washington, U.S., June 29, 2017. To match Special Report USA-NUKES/PLUTONIUM REUTERS/Carlos Barria/File PhotoReuters