Rex Tillerson, chief executive officer of Exxon Mobile Corp., left, listens on the opening day of the St. Petersburg International Economic Forum 2016 (SPIEF) in Saint Petersburg, Russia, on Thursday, June 16, 2016. The 20th anniversary St. Petersburg International Economic Forum which brings together heads of state and governments, political leaders, leading experts and global company executives runs from June 16-18. Photographer: Simon Dawson/Bloomberg via Getty Images
