New Haven

ONE of the great accomplishments of European integration - the passport-free movement of people across borders - is now exacerbating a crisis that threatens the core of the European project. European states are announcing tighter border members this week as the continent struggles to cope with tens of thousands of refugees, with more expected daily.

The European Union is racing to devise a solution to the crisis, the centrepiece of which is a plan by which all member countries will share the refugee burden. The crisis has illustrated broader challenges that Europe must address if it is to devise a long-term solution.