Does Iraq constitute a civil war?

Though still under dispute, a growing number of American scholars, leaders, and policy analysts, believe that Iraq does indeed meet the standard definition of a civil war. Accordingly,

...[S]ome scholars now say civil war began when the Americans transferred sovereignty to an appointed Iraqi government in June 2004. That officially transformed the anti-American war into one of insurgent groups seeking to regain power for disenfranchised Sunni Arabs against an Iraqi government led by Prime Minister Ayad Allawi and increasingly dominated by Shiites.

Analysts also claim that with the amount of casualties suffered in Iraq, the war is on par with civil conflicts in Burundi and Bosnia. Nicholas Sambanis of Yale remarks,

It's stunning; it should have been called a civil war a long time ago, but now I don’t see how people can avoid calling it a civil war...The level of violence is so extreme that it far surpasses most civil wars since 1945.

The significance of such definitional disputes are not limited only to semantics. Titling Iraq a civil war may have significant impacts on American foreign policy - according to the NYT, acknowledgement by the White House would mean an admission of failure of the administration's policy in Iraq. Furthermore, it might also encourage a greater demand for withdrawal from the public, who may view the role of American troops redundant in the context of a civil war. Just today, MSNBC announced that it is now referring to the war in Iraq as a civil war.