By Andrew North
BBC News, Baghdad
Is Iraq in a civil war or not? As sectarian killings continue, barely a day goes by now without someone fuelling the debate.
Many Iraqis face the prospect of random daily violence
The Saudi Foreign Minister Prince Saud al-Faisal and Egypt's President Hosni Mubarak are among those from outside Iraq who have recently declared that civil war is already under way or imminent.
From inside, Iraq's deputy interior minister said it started a year ago, while the former Prime Minister Iyad Allawi made similarly gloomy pronouncements last month.
Most Iraqi political figures - including the interior minister - have dismissed such talk.
However, some say they are partly responsible for making the situation worse, because of their continued delay in forming a government four months after elections.
But now one of the more influential analysts watching Iraq has decided that civil war is the right definition for what is going on now.
"To all intents and purposes, Iraq is in a civil war," Dr Toby Dodge, a veteran Iraq watcher based at London University's Queen Mary College, told the BBC.
So what is going on, and is it possible to define a civil war or not?
There are several reasons why many people argue Iraq has still not reached that point.
Despite the rise in sectarian killings after the bombing of the al-Askari shrine in Samarra in late February, they point out that the violence has not turned into full blown conflict between Shia and Sunni groups.
The attack on Baghdad's Baratha mosque angered Shias
There has been little change in the pattern since the triple suicide attack on a key Shia mosque in Baghdad last Friday, which killed at least 90 worshippers and which many feared could provide a final spark.
Another argument some make is that much of Iraq is relatively secure, with violence concentrated in just four governorates or provinces, among them Baghdad.
In 12 out of 18 provinces there are now just a handful of attacks, according to US military figures.
There is also a common belief that the structure of Iraqi society acts as a restraint on tensions boiling over, with its long traditions of intermarriage between Shias and Sunnis and different tribes.
However, history shows that a devastating internal conflict can still happen even if most of the country is unaffected.
At least 50,000 people died when Afghanistan descended into civil war in the early 1990s after the Soviet withdrawal, and the fighting was almost totally focused on the capital Kabul.
Intermarriage between different groups, although less common than in Iraq, made little difference in Afghanistan.
It is in Baghdad, with its mix of different communities, that the risk of all-out sectarian conflict is seen as highest. And if the capital is involved, that inevitably affects the whole country.
But the impact of sectarian tension is starting to be felt nationwide, with growing numbers of Sunnis or Shias leaving parts of the capital where they are in a minority.
Almost 11,000 families have now fled their homes since the bombing of the Samarra shrine, according to figures from the Iraqi ministry of displacement and migration.
Most move in with relatives or friends in areas where they feel safer, but many are going to camps run by the Red Crescent.
Some of these people have left their homes after being directly threatened, or after relatives have been killed.
"I never used to think about whether my neighbours are Sunni or Shia, even three months ago," said one Shia resident of Baghdad who has decided to move in with relatives in another part of the city.
"But after Samarra everything changed."
'Infrastructure of civil war'
It is this movement of people that is one reason why Toby Dodge says he has changed his view of the situation in Iraq.
He points to four indicators which have led him to conclude that the country is descending into civil war.
There is a "collapse in the authority of the central government", he says, accompanied by a rise in the power of local militias involved in sectarian violence.
Many Iraqi Shias have been roused to anger
Particularly worrying, Mr Dodge argues, is the increased "transfers of population" or displacement in recent weeks and increased evidence of "state institutions such as the police dividing along sectarian lines".
There has been concern for some time that police units under the control of the interior ministry have been infiltrated by Shia militias who are carrying out sectarian killings under official cover - a charge the interior minister has strongly denied.
But the Americans have recently been focusing attention on the activities of militias.
Without actually naming any groups, the US ambassador Zalmay Khalilzad called them "the infrastructure of a civil war" in a recent BBC interview and said they would have to be disbanded at some point.
Some say it does not matter what you call the current situation in Iraq.
"There is no clear or meaningful difference between insurgency and civil war, or between national terrorism and civil war for that matter," argues Anthony Cordesman, the influential Iraq expert at Washington's Centre for Strategic and International Studies.
But he goes on to say that Iraq's insurgency has evolved "in ways that increase the risk of intense or full-scale civil war.
"It is increasingly driven by sectarian and ethnic struggles, rather than national movements and causes."
The real concern, says Toby Dodge, is that once the dynamics of a civil war are set loose, they are very difficult to reverse.
"Only a government can do that, and there is no sign that is imminent."