ANTALYA, TURKEY - NOVEMBER 15:  British Prime Minister David Cameron (L) shakes hands with Japanese Prime Minister Shinzo Abe during a bilateral meeting  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 - Pool/Getty Images)