Parts of downtown Hamburg, the second-largest city in Germany, resembled a war zone after hundreds of supporters of the jihadist group Islamic State [IS] engaged in bloody street clashes with ethnic Kurds. The violence—which police say was as ferocious as anything seen in Germany in recent memory—is fueling a sense of foreboding about the spillover effects of the fighting in Syria and Iraq. Some analysts believe that rival Muslim groups in Germany are deliberately exploiting the ethnic and religious tensions in the Middle East to stir up trouble on the streets of Europe.