[France's President Francois Hollande, right, and German Chancellor Angela Merkel arrive to pose for a family photo during the Balkans summit, at the Elysee Palace, in Paris, Monday, July 4, 2016.The leaders of France, Germany, Italy and Balkan nations are meeting to better prevent extremists from sneaking in with migrants who are moving west across Europe. (AP Photo/Thibault Camus, Pool)]BRUSSELS (AP) — The European Union has known some crises in its time: the constitution that never was, impossible budget deals, debt devastating the Greek economy and threatening the euro currency, strife as nations failed to manage the continent's refugee emergency together.