Crises bring Europe to the brink of chaos
Popular Greek opposition to their bailout deal has, for the first time, given normally confident EU leaders pause for thought about their assumptions of "ever-closer union".
The scale of Greece's No vote came as a shock, but worse for the leaders is that it is just one of a series of crises facing Brussels.
A poisonous row over migration, the split over sanctions against Russia, and the prospect of a British exit leaves Brussels with its most uncertain and dangerous summer since its origins as a trade pact in 1951.
Institutions long seen as permanent and inviolable - including the single currency and the Schengen free-travel zone - have never looked so fragile.
"Everything seemed so self-evident for decades, and now so many achievements that we have so laboriously built are being severely tested," said Frank-Walter Steinmeier, the German foreign minister.
A blueprint drawn up to create a new EU treasury and strip more powers from members over budgets is now in doubt after one of its architects appeared to disown it.
Last month, European foreign ministers agreed to roll over sanctions on Russia until the end of the year in response to the annexation of Crimea and the incursion into east Ukraine.
However, the consensus is shaky, and Alexis Tsipras, the Greek premier, has made it clear he will look to the Kremlin for financial help if he has to - a move likely to kill the unanimity needed for sanctions.
At the same time, the migration crisis in the Mediterranean has exposed the fragility of EU solidarity. Finally, European leaders know that Britain's exit from the EU would deal a permanent blow to its ambitions and finances. Rem Korteweg, of the Centre for European Reform, said the parallel crises would unleash "chaos, instability and mutual recrimination". (© Daily Telegraph, London)