By Roger Hardy
BBC News Middle East Analyst
As sectarian killings continue in Iraq, some Shia politicians, including government ministers, are stepping up their calls for the country's partition. Some prominent figures in Washington are saying the same. So does Iraq have a future as a unified state?
The idea that three Iraqs are better than one has been around for a while.
But it is now being expressed, in Baghdad and in Washington, with a new vigour.
The mounting death toll in Sunni-Shia violence is giving the idea a fresh impetus.
One of the most prominent Shia political leaders, Abdel-Aziz Hakim, is pushing more aggressively for a Shia 'super-region' embracing half of the country's provinces and more than half of its oil reserves.
A senior Iraqi government official, speaking anonymously to Reuters, recently declared: "Iraq as a political project is finished."
Education Minister Khudair Khuzai, a Shia, has told the Los Angeles Times: "Federalism will cut off all parts of the country that are incubating terrorism from those that are upgrading and improving."
The region to be cut off is, by clear implication, the Sunni heartland north and west of Baghdad.
Equally clearly, the regions that are 'upgrading and improving' are the Kurdish north and the Shia south.
"We will do it just like Kurdistan," the minister added. "We will put soldiers along the frontiers."
In Washington, meanwhile, some prominent figures are echoing the theme.
A former US diplomat, Peter Galbraith, has just published a book called The End of Iraq.
The country has already broken up, he argues, and even the American superpower cannot put it back together again.
A senior Democratic senator, Joseph Biden, has also come out in favour of partition.
But critics of the idea are equally vocal.
Formally partitioning Iraq, they argue, would be messy and violent, and the outcome would not necessarily be stable.
The Kurds of the north and the Shia in the south would become the masters of Iraqi oil, leaving the Sunni Arabs an impoverished and alienated minority.
Senator Biden supports the idea of partitioning Iraq
Partition would tempt outside powers, Iran, Syria, Saudi Arabia and Turkey, to intervene.
Some of those advocating a three-way split are, like Mr Galbraith, strong supporters of the rights of the Iraqi Kurds.
But what is good for the Kurds is not necessarily good for Iraq as a whole.
Mr Galbraith's arguments may also be based on a misreading of Iraqi history.
He writes of a 'coerced unity', suggesting that Saddam Hussein imposed unity on an unwilling nation.
But this is to underplay the degree to which the 'idea of Iraq' had taken root.
For decades, there was intermarriage between Sunni and Shia and between Arab and Kurd.
For decades, Baghdad was the great melting pot of all communities.
It is only recently that the idea of a single, united Iraq has been seriously called into question.
Now, under the pressures of 'sectarian cleansing', the country is moving inexorably towards greater fragmentation.
Iraq's future is likely to be determined by events on the ground rather than by the speeches of politicians.
One man who, for reasons of his own, remains firmly committed to a united Iraq is US President George W Bush.
The president would prefer to be remembered as the leader who freed Iraq from dictatorship rather than as the man who split it apart.