When Britain formally left the European Union, many governments breathed a sigh of relief. For the first time in decades, they said, the British will not be able to torpedo European foreign policy and security initiatives; at long last, Europe could talk with one voice. And the omens got even better once the White House was occupied by a president who is not instinctively suspicious of European foreign policy initiatives.

And yet last week's EU summit was a mess. A proposal put forward by French President Emmanuel Macron and German Chancellor Angela Merkel to start a new security dialogue with Russia was angrily shot down by the central and east European members of the bloc and no amount of cajoling or diplomatic finessing worked.