A man holds his hands up behind a chain link fence as Pakistani and Afghan migrants protest inside the Moria detention center in Mytilene on the Greek island of Lesbos on April 5, 2016 against deportation to Turkey.
Migrant returns from Greece to Turkey begun on April 4 under the terms of an EU deal that has worried aid groups, as Athens struggles to manage the overload of desperate people on its soil. Over 51,000 refugees and migrants seeking to reach northern Europe are stuck in Greece, after Balkan states sealed their borders. Hundreds more continue to land on the Greek islands every day despite the EU deal. / AFP / ARIS MESSINIS (Photo credit should read ARIS MESSINIS/AFP via Getty Images)