BRATISLAVA, Slovakia: If Britain long felt like a sore festering at the heart of European unity, its planned departure has made one thing clear: It's far from the only malaise for the vision of a common European Union future.
Brexit comes on top of a refugee emergency that EU nations simply cannot agree how to manage.
Only Wednesday, French far-right leader Marine Le Pen promised a referendum on France's place in the EU should she seize the presidency next year.
Against this backdrop, Tusk is hoping for an "honest assessment" of how the EU got itself into this fundamental political quagmire where distrust has replaced half a century of optimism as the EU expanded from a core of a half-dozen west European neighbors to a wealthy group of 28 nations making up the world's largest trading bloc.
The one-day Bratislava summit should be the first in a number of confidence-building meetings where a road map should be set up to culminate in a March summit in the Italian capital, when the 60th anniversary of the EU's founding Treaty of Rome will be marked – or, in the best of circumstances, celebrated.