Homeward Bound?

On May 24, 2014, a man opened fire inside the Jewish Museum in Brussels, quickly killing three people and fatally wounding a fourth before disappearing into the city’s streets. The alleged perpetrator, a French citizen named Mehdi Nemmouche, who has since been arrested and charged with murder, had spent the previous year fighting with jihadist opposition groups in Syria. His attack appeared to mark the first time that the Syrian civil war had spilled over into the European Union. Many security officials in Europe and the United States fear that this strike foreshadowed a spate of terrorist attacks that the chaos in Syria—and now Iraq—could trigger.

The Syrian conflict has captured the imaginations and inflamed the passions of Muslims around the world, spurring thousands to join the mostly Sunni rebels resisting the Assad regime. The influx of volunteers has bolstered jihadist groups such as the Islamic State of Iraq