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Sunni and Shiite clerics gunned down. Christian churches bombed. Hundreds of police killed, and Iraqi soldiers abducted and threatened with death.

Is Iraq heading to civil war?

No way, say Prime Minister Ayad Allawi (search) and many of his countrymen, who blame the bloodshed on foreign Islamic extremists.

However, as the death toll rises, thoughtful Iraqis are beginning to fear the unthinkable.

"We are not yet in a civil war," said Mahmoud Othman, a senior Kurdish politician and member of the former Iraqi Governing Council (search). "But if the ongoing violence is not contained, it will turn into an Iraqi-Iraqi war."

Many Iraqis put their faith in age-old ties among Shiites, Sunnis and Kurds to keep the peace — an understandable yearning, perhaps, since most Iraqis don't want to imagine things getting any worse.

But these ties, which are in large part confined to the cities, are fraying as security becomes more precarious and violence spreads.

"The lessons of Bosnia indicate that communities that have lived in relative harmony can embrace sectarian divisions overnight," warns a report by London's Royal Institute of International Affairs.

One result, it says, could be Iraq's fragmentation into a Kurdish north, Sunni center and Shiite south.

Scores of Shiite and Sunni clerics as well as Kurdish and ethnic Turkish politicians have been killed over the past year in what are widely believed to be sectarian-driven murders.

Sunni and Shiite mosques have been bombed in tit-for-tat revenge attacks and Christian churches in Baghdad also have been targeted. Growing numbers of Shiites and Sunnis fear being caught in the wrong place. Arabs are treated with suspicion in Kurdish areas.

Policemen and the Iraqi National Guard (search), playing a growing role in the U.S.-led anti-insurgency fight, have become a target of terror bombings. If U.S. military commanders go ahead with plans to deploy them in "no-go" Sunni areas, more Iraqi-Iraqi bloodshed is sure to result.

A classified report by the U.S. National Intelligence Council presented President Bush this summer with several bleak scenarios, one of them envisioning civil war before the end of 2005.

In a front-page editorial Monday on the U.S. intelligence report, Iraq's pro-government daily al-Sabah warned against ignoring the threat of a civil war.

"The problem is political," wrote the paper's editor, Mohammed Abdel-Jabar. Only a political solution can head off "a civil war that, yes, doesn't seem imminent, but which is not impossible," he added.

Iraq's sectarian passions, long held in check by Saddam Hussein, have become more pronounced with the almost unbridled liberties that took root following the U.S. invasion. All sides are afraid of being overrun by the other — the Sunni minority by the Shiite majority, the Kurds by both. And all feel obliged to look to the worst-case scenario of the Americans withdrawing and leaving each group to fend for itself.

Secessionist sentiments are growing among the Kurds, who have a well-armed and battle-tested militia and fear losing the de facto independence they have enjoyed under Western protection since 1991.

The minority Sunnis are bristling over losing their traditional place at the top of the pecking order to the 60 percent Shiite majority, whose secular and spiritual leaderships are united in the quest for political domination.

Clerics have not proven immune to the violence.

Since Saddam's ouster 17 months ago, two incidents brought Shiites and Sunnis close to a sectarian war: the death of senior Shiite cleric Ayatollah Mohammed Baqir al-Hakim in a car bomb outside the Imam Ali shrine in the holy city of Najaf; and the death seven months later in bomb blasts of nearly 200 Shiite pilgrims visiting shrines in Baghdad and Karbala.

Many Shiites blamed Sunni militants and Saddam loyalists, and the death of al-Hakim triggered a wave of attacks targeting Sunnis.

On Sunday and Monday, two Sunni clerics were gunned down in Baghdad — attacks which Sheik Abdel-Sattar Abdul-Jabar of the influential Sunni group Association of Muslim Scholars (search) blamed on "the occupation forces and some (Iraqi) sectarianists."

It is not uncommon for Iraqis to ascribe anything that goes wrong on the United States. In fact, many say that the United States, in trying to redress Saddam era injustices, has inflamed sectarian sentiments by showing bias in favor of the Shiite and Kurds, the two communities that suffered the most under the dictator's 23-year rule.

Contrasting perceptions of the Saddam legacy also have deepened the Shiite-Sunni divide.

The Sunnis, for example, are reluctant to believe that Saddam ordered the killing of tens of thousands of Shiites and Kurds and buried them in mass graves while suppressing their 1991 uprisings. The question of mass graves is very sensitive to Shiites and Kurds, who view Sunni denials of Saddam's crimes as a serious obstacle to reconciliation.

Some Shiites, on the other hand, blame the violence on Sunni militants, rather than the Americans.

"I don't think there will be a civil war in Iraq because the Americans are here," said Abdul-Kazim Ilawyi, a 57-year-old engineer from Baghdad's mainly Shiite Kazimiyah district.

"I am all for attacking them (insurgents) in Fallujah and their other strongholds because they are responsible for the mess we are in," he said, referring to the Sunni city west of Baghdad where U.S. warplanes are bombing suspected militant hideouts almost daily.

Allawi, a secular Shiite whose three decades in exile have left him with no real power base, insists there is no reason to fear the worst.

"We (have) kept all the constituencies of Iraq talking to each other," he said in an interview broadcast Sunday on ABC's "This Week." "There is, yes, disintegration of law and order, yes, there is. But I would not categorize it as a precursor for civil war."