ANTALYA, TURKEY - NOVEMBER 15:  Russian President, Vladimir Putin (R) is greeted by Turkish President Recep Tayyip Erdogan, during the official welcome ceremony on day one of the G20 Turkey Leaders Summit on November 15, 2015 in Antalya, Turkey. World leaders will use the summit to discuss issues including, climate change, the global economy, the refugee crisis and terrorism. The two day summit takes place in the wake of the massive terrorist attack in Paris which killed more than 120 people.  (Photo by Chris McGrath/Getty Images)