When is a Civil War a "Civil War?"

Since the Bush Administration announced "Mission Accomplished" 1,190 days ago, sectarian violence errupted betwen the Sunni and Shi'a and one of the main obstacles to stability in Iraq. The division between the groups is not major news since these two groups have been fighting a political battle since 632 C.E. over succession of leadership after the Death of the Prophet Muhammed. The current Iraq War and the lack of security after the war only exacerbated this division and violence.

But who has the power to define the Civil War in a Iraq a "Civil War." Isn't this question important to the fall mid-term elections?