[Turkey's EU Affairs Minister Volkan Bozkir addresses the media after a meeting with Belgium Foreign Minister Didier Reynders at the Egmont Palace in Brussels on Thursday May 12, 2016. (AP Photo/Geert Vanden Wijngaert)]BRUSSELS (AP) — The number of migrants arriving in Greece has plummeted thanks in part to the European Union's pact with Turkey, the EU border agency said Friday, amid signs that the widely-criticized agreement to stop people heading to Europe could unravel.