The grand Shiite-Sunni struggle

Why is the Middle East in turmoil?In a half-dozen nations, tyrants who once ruled by fear and repression have been toppled, unleashing centuries-old sectarian rivalries and bloody struggles for power. Syria's horrific civil war is spilling into Lebanon and threatening Jordan and Turkey, while Iraq has effectively devolved into three nations -- one Shiite, one Sunni, one Kurdish. In the chaos, a particularly malignant form of radical Sunni Islam, the Islamic State of Iraq and Syria, or ISIS, has ...