US President Barack Obama (L) and Chinese President Xi Jinping (R) attend the opening ceremony of the G20 Summit at the International Expo Center in Hangzhou on September 4, 2016. G20 leaders confront a sluggish global economy and the winds of populism as they open annual talks, but the long war in Syria and the South China Sea territorial dispute hang over the summit. / AFP PHOTO / POOL / Nicolas ASFOURINICOLAS ASFOURI/AFP/Getty Images