Police escort migrants and asylum seekers as they walk to a refugee centre after crossing the Croatian-Slovenian border near Rigonce on October 24, 2015. Bulgaria, Romania and Serbia threatened to close their borders if EU countries stopped accepting migrants, as European leaders prepared for a mini summit on the continent's worst refugee crisis since World War II.  / AFP / Jure Makovec        (Photo credit should read JURE MAKOVEC/AFP/Getty Images)