Like the crude oil that lies in vast pools be-neath the Persian Gulf, tensions between the region's Sunni and Shia Muslims tend to stay below ground. But when pressures build and a ready channel is cleared, they can bubble to the surface with alarming force. Thirty years ago the Islamic revolution in Shia-majority Iran inspired a wave of unrest among fellow Shi-as of the opposite shore. Things then calmed down. Nervous Arab rulers, all of them Sunnis, soothed their Shia subjects with a few rights and promises of more, while Iran largely gave up trying to export its revolutionary fervour.rnBut with Iran lately sounding more aggressive under President Mahmoud Ah-madinejad, small incidents are again triggering bigger eruptions. On February 20th, for instance, a group of female pilgrims vis-
展开▼
