Civil War Confirmed
Thanks to Juan Cole, we have a definition of civil war and can describe Iraq as such:
"Sustained military combat, primarily internal, resulting in at least 1,000 battle-deaths per year, pitting central government forces against an insurgent force capable of effective resistance, determined by the latter's ability to inflict upon the government forces at least 5 percent of the fatalities that the insurgents sustain."
(Errol A. Henderson and J. David Singer, "Civil War in the Post-Colonial World, 1946-92," Journal of Peace Research, Vol. 37, No. 3, May 2000.)