European Union leaders are holding an emergency summit later today in an attempt to address the worsening immigration crisis. Nobody doubts the urgency of the task. As Hungarian Prime Minister Viktor Orban graphically put it, the waves of asylum seekers are "breaking the doors" of Europe.

EU officials appear to have dropped plans to force European states to share the current immigration burden. Instead, countries will be invited to accept the settlement of refugees on a "voluntary" basis, a compromise that will produce the same result but which preserves the sovereignty of states.

Still, with the number of refugees and asylum seekers arriving in Europe estimated to reach a record 1.2 million by the end of this year - more than double the figure last year - merely relocating existing migrants is not a long-term solution.

All eyes today will be on German Chancellor Angela Merkel, the only leader able to broker a longer-term immigration deal. She stands accused by most Europeans of making a bad situation worse by offering to open Germany's borders to all newcomers. Germany has since reimposed border controls but has not said if these are permanent. And until Dr Merkel brings some clarity to this, it is in the interest of the other countries through which migrants pass to continue pushing them towards Germany, thereby perpetuating the flow.

In short, the human convoys that now cross from southern Europe through Hungary, Austria and through to Germany can be stopped only if Germany adopts a more restrictive immigration policy, and encourages others to do the same.

But what Europe needs most is to restore its internal cohesion, for the refugee crisis has divided the continent between East Europeans, who have no previous experience with immigration, and West Europeans, who are more lenient. Unless this rift begins to be addressed today, Europe risks destroying its most precious achievement to date: its open frontiers and free movement of its people.