Iraqi rift endangers unity government
Barely had the last American soldier stepped across the border into Kuwait than the fragile Iraqi political structure the US military left behind began to fall dangerously apart, as long-standing tensions between Shia and Sunni political leaders came to a head.
The most dramatic symptom of the exploding crisis is the fact that Iraq's most senior Sunni Arab politician, Vice-President Tariq al-Hashemi, is effectively a fugitive, with an arrest warrant on terrorism charges hanging over his head.
While he hides out under Kurdish protection in the north, the entire al-Iraqiyya political bloc to which he belongs has pulled out of both parliament and the cabinet.
That paralyses Sunni participation in the hard-won power-sharing deal that underpins a year-old national unity government which has rarely pulled together.
Frantic efforts are now under way to try to hold that structure together.
The alternative, at its direst, could be the country's de facto partition, as part of a wider regional Balkanisation along sectarian lines.
Much will depend on the outcome of the current struggle in neighbouring Syria.
Some analysts see the Syrian conflict, coinciding with the US withdrawal from Iraq, as a major factor in the emergence and timing of the Iraqi crisis.
Just as regime change in Iraq brought the majority Shia to power, the collapse of President Bashar al-Assad's government in Damascus would inevitably mean the empowerment of Syria's Sunni majority.
The areas of Iraq adjacent to the country's long border with Syria are almost entirely Sunni-dominated.
As the crisis in Syria deepened in recent weeks, there have been two significant developments in Iraq.
Sunni-majority provinces which had previously shunned the idea of setting up Kurdistan-style autonomous areas, as the new constitution allows, have begun to embrace that idea, to the clear displeasure of the Shia Prime Minister, Nouri Maliki.
His Shia-dominated administration, with all the security agencies under his personal control, has simultaneously been conducting an aggressive campaign to detain people - inevitably, mainly Sunnis - suspected of sympathies or affiliations with Saddam Hussein's now-banned Baath Party and its surviving adherents, some of whom took refuge in Syria.
"Maliki and the Shia are paranoid about the emergence of a Sunni Syria with Baathist and Salafist tendencies", said one senior Iraqi politician.
Baathists and militant Islamic jihadis made up the two main strands of the Sunni-based insurgency which killed many thousands of Shia during the sectarian carnage of 2006 and 2007, and which continues in much-reduced form.
Islamist activists are believed to be involved in the armed opposition to the Syrian government, which was earlier accused by Baghdad and Washington of allowing them to cross the border and carry out bomb attacks in Iraq.
"We warned them at the time that they were holding the tail of a snake, and it would turn and bite them," said one Iraqi leader. "Now it is happening."
Sunni sources in Iraq say that arms are being smuggled across the border from the Mosul and al-Anbar areas to anti-regime activists inside Syria.
So the Iraqi Shia factions are haunted by the spectre of the emergence of a new power bloc linking a Sunni Syria with Sunni parts of Iraq which are seeking autonomy.
Shia anxiety is founded not only on what happened during the insurgency, but also under Saddam Hussein's Sunni-dominated Baath Party, which generally suppressed the Shia and killed thousands during successive uprisings.
But there is anxiety and suspicion on the Sunni side too, and a gulf of mistrust between the two sides.
Sunni leaders accuse Prime Minister Maliki and his Shia allies of being hand-in-glove with Iran, and bent on turning the country into a Persian satrapy.
They charge that he has monopolised power by keeping control of the still-vacant defence and interior ministries, making himself almost entirely in charge of a security apparatus which they assert has been increasingly victimising Sunnis.
"The political process which is supposed to have brought democracy to Iraq, in fact brought one party and one person who are ruling Iraq," said Deputy Prime Minister Saleh al-Mutlak, another senior Sunni figure, referring to Mr Maliki and his Shia Daawa Party.
"There is no real participation by others, and the country is heading towards a harsh, backward dictatorship without a shred of wisdom."
"I fear that the vacuum caused by the absence of political agreement will lead to the partitioning of the country, a partition preceded by wars and followed by wars over boundaries and natural resources," he told the BBC.
In another sign of the gaping rift between the Shia and Sunni leaderships, Mr Maliki has formally asked parliament to impeach Mr Mutlak, his own deputy, because of such incendiary statements.
The power-sharing deal which was hammered out through nine months of tortuous post-election wrangling and which underpinned the national unity government's formation exactly a year ago, is now clearly in danger.
So says the man who played the key role in forging the understanding, the Kurdish leader Masoud Barzani, President of Iraqi Kurdistan.
The power-sharing deal was never properly implemented. It called for the formation of a National Strategic Council as a vehicle for the al-Iraqiyya list leader, Iyad Allawi, to share power with Mr Maliki.
The project never reached fruition, and Mr Allawi - a secular Shia who won practically all the Sunni votes - has largely bowed out of the picture, leaving the Sunnis complaining of marginalisation.
Mr Allawi's al-Iraqiyya bloc came out narrowly ahead in the polls, but was outmanoeuvred as Mr Maliki assembled an alliance of almost all the Shia factions, with the deciding role played by the Iranian-backed militant Shia cleric, Moqtada Sadr.
The understanding sponsored by Mr Barzani had a green light from both Iran and the US, something the Kurds are uniquely placed to achieve, just as they alone among the Iraqis can mediate between the country's feuding Sunni and Shia Arab leaders.
The Kurds are bound to renew that key role in the coming days of intense efforts to revive - or perhaps revise - the national entente formula.
In recent years, the Americans would have been expected to head off such a rift long before it happened.
The White House has said it is deeply concerned by the current crisis and has been in touch with all sides.
Its ability to continue playing a major role in the Iraqi political arena in the post-withdrawal period is thus faced with an immediate test, but the Iraqi perception is that US influence is now much diminished.
The crisis may also give clues as to how hard Tehran will seek to push its advantage and exploit the perceived vacuum left by the American withdrawal.