The power vacuum created by the fall of the regime has allowed tribalism and religious and ethnic factionalism to re-emerge in Iraq after decades of suppression, writes Michael Jansen
So far, there have been confrontations between tribal groups, heterodox Shia Muslim factions and clashes between Shia and orthodox Sunni Muslims, Kurds and Arabs, and Kurds and Turkomen. The potentially violent permutations in Iraq's communal mosaic are endless.
British forces were the first to deal with Iraq's complex communal patchwork when they attempted to administer and police Basra, with a population of 1.7 million. The British engaged the help of a tribal chief to end lawlessness and looting, but he was promptly accused of having collaborated with the Baathist regime.
The British had no choice but to stick with him and to recruit other former Baathists to run the city. But, by doing so, the British forces alienated traditional opponents of the chosen tribe.
The next challenge to the occupying forces came on Thursday when a mob in the Shia holy city of Najaf hacked to death Sayyed Abdel Majid al-Khoei, who had returned from exile in Britain and was attempting to reconcile warring factions. He was allegedly killed by adherents of Muktada al-Sadr, the son of Ayatollah Muhammad al-Sadr, a senior cleric murdered by the regime in 1999.
Mr al-Sadr's faction was also responsible for threats issued against three other Shia clerics, Grand Ayatollah Ali al-Sistani, Ayatollah Muhammad Fayyad and Ayatollah Muhammad Said al-Hakim. Last Saturday, a mob demonstrated outside the homes of Ayatollah al-Sistani and Ayatollah Fayyad, demanding that they quit Iraq within 48 hours. On Sunday, tribesmen apparently entered Najaf and liberated it from Mr al-Sadr's group.
While his strongmen may have been driven from Najaf for the present, Mr al-Sadr's faction has established a strong presence in key sectors of the sprawling "Thawra" (Revolution) suburb of Baghdad, renamed "Medina Saddam" (Saddam City) after the rise to power of the former president, Saddam Hussein.
Some now call this area "al-Sadr City", to honour the slain ayatollah. But the new name could be disputed by other Shia factions. The flags flying over this quarter, inhabited by two million of the capital's five million people, are the green and black standards of the Shias rather than Iraq's red, white and black tricolour with green stars.
Some clerics are calling for an Islamic state, modelled on Iran, and argue that the Shias - 60 per cent of the population of Iraq - must rule, since they form a clear democratic majority.
Tensions between Shias and Sunnis are running high in the capital after poor residents of the Shia slums were accused by more prosperous Sunnis of ransacking the ministries, pillaging Iraq's National Museum and looting private shops and homes. Sunni property-owners have set up roadblocks and mounted armed patrols to keep looters at bay.
On Sunday, eight people were killed in clashes between Kurds and Arab tribesmen near the northern town of Huwaija after Kurds looted the oil cities of Kirkuk and Mosul. Arab homeowners appealed to US forces to halt the pillage. Turkomen (ethnic Turks) displayed the body of a seven-year-old boy killed by Kurdish gunmen and called on Turkey to intervene.
In Kirkuk and neighbouring villages, Arab and Muslim and Christian and Turkomen families are being ethnically cleansed by Kurds seeking to return to an area from which they were expelled two decades ago in the Baathist government's drive to Arabise the Kirkuk and Mosul regions so that they could not be claimed by Kurds seeking to establish a separate state.
As long as the power vacuum continues, communal score-settling could be followed by personal score-settling against former Baathist office-holders and others who prospered during the fallen regime.
Ahead of the war, both western and Iraqi analysts warned that the strong hand of Saddam Hussein would have to be promptly replaced with equally firm control by the US and Britain if post-war conflicts were to be avoided and civil war averted.