For three decades multiculturalism has been the focus of fierce debates. At the same time Europeans have worried, at the national level and at that of the European Union, about how to relate to a world in which their influence has been steadily reducing. But the two discussions, on society and on foreign policy, have rarely intersected. The events of 11 September 2001 did shock the citizens of Western countries into an awareness that international politics could literally explode onto their home streets, and generated fear and suspicion about and among minority groups. But the excessive focus...