Venezuela's President Nicolas Maduro (centre R), Iranian President Hassan Rouhani (centre L) and other presidents, leaders and head of delegations pose for a family photo during the 17th Non-Aligned Summit in Porlamar, Venezuela September 17, 2016. REUTERS/Marco Bello

Venezuela's President Nicolas Maduro (R) welcomes Bolivia's President Evo Morales to the 17th Non-Aligned Summit in Porlamar, Venezuela September 17, 2016. REUTERS/Marco Bello

William Canterbury of Birmingham, Alabama, fills his vehicle with gas at a Twice Daily gas station on Franklin Road in Brentwood, Tennessee, U.S. September 17, 2016. REUTERS/David Mudd

Out of fuel signs are pictured on gas pumps at a Twice Daily Shell station on West End Ave. and N. 17th Ave. S. in Nashville, Tennessee, U.S. September 17, 2016. REUTERS/David Mudd

Out of fuel signs are pictured on gas pumps at a Mapco gas station at Spence Lane and Lebanon Pike in Nashville, Tennessee, U.S. September 17, 2016. REUTERS/David Mudd

Vehicles wait in line for gas at a Twice Daily gas station on Franklin Road in Brentwood, Tennessee, U.S. September 17, 2016. REUTERS/David Mudd

Vehicles wait in line for gas at a Twice Daily gas station on Franklin Road in Brentwood, Tennessee, U.S. September 17, 2016. REUTERS/David Mudd

A Syrian refugee rides a bicycle with his daughter at the main market, in the Al-Zaatri refugee camp in the Jordanian city of Mafraq, Jordan, near the border with Syria September 17, 2016. REUTERS/Muhammad Hamed