WASHINGTON, (UPI) -- - The Iraq war now threatens stability throughout the Gulf region, a leading U.S. analyst warns in a new report released this week.

"The rising insurgency in Iraq has become a "war after the war" that threatens to divide the country and thrust it into full-scale civil war. It dominates the struggle to reshape Iraq as a modern state, has emerged as a growing threat to the Gulf region, and has become linked to the broader struggle between Sunni and Shiite Islamist extremism, and moderation and reform, throughout the Islamic world," states the new report.

The report is entitled "Iraq's Evolving Insurgency and the Risk of Civil War: Democracy, Deadlock, and Death Squads: Developments in the Summer of 2006." It was published by the Center for Strategic and International Studies, an influential Washington think tank, and it was written by Anthony H. Cordesman, who holds the Arleigh A. Burke chair in strategy at CSIS.

"In the summer and fall of 2006, Iraqis faced unprecedented levels of violence, carried out by a tangled set of warring factions. As the nature of the insurgency became more complex, the prospects for national reconciliation grew more distant," the report said.

Cordesman warned that "Ethnic and sectarian fighting was eclipsing the dominant threat posed by Sunni insurgents, both in terms of inflicting the majority of Iraqi casualties, as well as hindering political, social, and economic progress in the country."

"Violence carried out by Sunni and Shiite factions appeared to be carving Baghdad, and the country as a whole, into sectarian zones, protected by various armed groups" he said. "Increasingly, violence became part of a sectarian struggle for territorial gains."

Compounding the grim picture, Cordesman said, "Attack patterns indicated an upsurge in civilian casualties."