Unrest in Iran, OPEC's fourth-largest producer, is also underpinning crude prices as Iranian security forces have killed thousands of protesters, and President Trump threatened attacks on Iran if the killing of protesters continues. Reuters reported last Wednesday that some US personnel have been advised to leave the US Al Udeid Air base in Qatar. The facility was targeted by Iran in retaliatory airstrikes last year after the US attacked Iran's nuclear facilities. Iran, OPEC's fourth-largest producer, produ ...