IDOMENI, GREECE - MARCH 14: Migrants try to cross a river after leaving the Idomeni refugee camp on March 13, 2016 in Idomeni, Greece. The decision by Macedonia to close its border to migrants on Wednesday has left thousands of people stranded at the Greek transit camp. The closure, following the lead taken by neighbouring countries, has effectively sealed the so-called western Balkan route, the main migration route that has been used by hundreds of thousands of migrants to reach countries in western Europe such as Germany. Humanitarian workers have described the conditions at the camp as desperate, which has been made much worse by recent bouts of heavy rain. (Photo by Matt Cardy/Getty Images)

IDOMENI, GREECE - MARCH 14:  Migrants try to cross a river after leaving the Idomeni refugee camp on March 13, 2016 in Idomeni, Greece. The decision by Macedonia to close its border to migrants on Wednesday has left thousands of people stranded at the Greek transit camp. The closure, following the lead taken by neighbouring countries, has effectively sealed the so-called western Balkan route, the main migration route that has been used by hundreds of thousands of migrants to reach countries in western Europe such as Germany. Humanitarian workers have described the conditions at the camp as desperate, which has been made much worse by recent bouts of heavy rain.  (Photo by Matt Cardy/Getty Images)