WASHINGTON (CNN) -- The latest National Intelligence Estimate on Iraq says the phrase "civil war" "does not adequately capture the complexity of the conflict in Iraq," according to the declassified portion of the report issued Friday.

But intelligence officials said the much-debated term "accurately describes key elements of the Iraqi conflict, including the hardening of ethno-sectarian identities, a sea change in the character of the violence, ethno-sectarian mobilization, and population displacements."

The estimate notes that the conflict is particularly complex because it includes "extensive Shia-on-Shia violence, al Qaeda and Sunni insurgents attacks on coalition forces, and widespread criminally motivated violence."

These are among the key judgments in the estimate, a 90-page document, called "Prospects for Iraq's Stability: A Challenging Road Ahead."

"Iraqi society's growing polarization, the persistent weakness of the security forces and the state in general, and all sides' ready recourse to violence are collectively driving an increase in communal and insurgent violence and political extremism," the report said.

"Unless efforts to reverse these conditions show measurable progress during the term of this estimate, the coming 12 to 18 months, we assess that the overall security situation will continue to deteriorate at rates comparable to the latter part of 2006."