Compared with many bombs in Iraq, it was not a big one. I had just arrived in the Al Rashid Hotel in Baghdad on 28 November when there was the an explosion a few hundred yards away in front of the parliament building. I thought at first it must be a rocket or a mortar shell fired from outside the Green Zone, but, as night was falling, I drove past the site, which was marked by the burned-out chassis of a car that looked as if a bomb had detonated inside it. I could see no crater, indicating that the explosive must, by Baghdad standards, have been on the small side.
I had no idea at the time that this explosion would mark a significant change of direction in Iraqi politics. It may only have been used as an excuse, but the bomb was the signal for the Prime Minister, Nouri al-Maliki, to cut adrift the senior Sunni members of his government. He said the bombing was an elaborate attempt to assassinate him and accused the bodyguards of Vice-President Tariq al-Hashemi of involvement. An arrest warrant was issued for Mr Hashemi, accusing him of running a death squad, with most of the charges relating to 2006-07. Mr Hashemi was forced to flee to Kurdistan; once there, he denounced the Maliki government as a dictatorship.
Is this the final disintegration of Iraq? Is Mr Maliki turning into a Shia version of Saddam Hussein, abandoning compromise, centralising power and relying on force alone? Does he have the means to do so? Even with Iraq's $100bn-a-year oil revenues, a large if chaotic state machine and security forces numbering 900,000 soldiers and policemen, it will not be that easy.
Saddam had far greater means of coercion and still failed to establish his absolute power. He failed because Iraq's three main communities – Shia, Sunni and Kurd – are hard to intimidate permanently. He and previous rulers used massacre and terror against the Kurds for more than 40 years, but were unable to crush them. "The Sunni Arabs are in a better position to destabilise Iraq than the Kurds ever were," says one Iraqi observer.
The centralising of power in Iraq faces such great obstacles because all parties have foreign allies and, under pressure, will call on them. The Sunnis in Iraq will look to Saudi Arabia, Qatar, Turkey and the US if they are marginalised and turned into second-class citizens. Though not quite there yet, some Sunni politicians in Baghdad have been leaving with their families, on the grounds that it is too dangerous to stay.
Mr Maliki may appear to have an advantage in physical power, but this is deceptive. His armed forces are numerous, but ramshackle and often ineffective. Al-Qa'ida in Mesopotamia is not that big, but it still managed to plant more than a dozen bombs in Baghdad on 22 December.
More important, Mr Maliki's leadership was the result of a compromise when he was first chosen as prime minister in 2006 and again in 2010. He has always had many enemies, but they proved too disunited to choose an alternative candidate acceptable to them all. Kurdish politicians and followers of the nationalist Shia cleric Muqtada al-Sadr all denounced Mr Maliki as untrustworthy and dictatorial during his first term in office, but ended up joining his new government.
As important is the fact that Mr Maliki is perhaps the only leader acceptable to the US and Iran. Because the Americans and Iranians spend so much time insulting each other over Iraq, too little attention is given to their unspoken accommodations there. In 2006 and 2010, Mr Maliki was the beneficiary of this. When he was selected, an Iraqi official told me with a laugh: "The Great Satan [as the Iranians call the US] and the Axis of Evil [as the US describes Iran and its allies] have come together again and chosen Maliki as their man."
It is a policy that has had its opponents abroad. "I think it was a bad mistake for the US not to say in 2010 that Maliki was unacceptable to them," said a Western diplomat formerly posted to Baghdad. He argued that Mr Maliki should have been rejected because he was a sectarian Shia intent on building an authoritarian state and that this state is corrupt and dysfunctional. Corruption is at a level whereby state funds are simply transferred abroad to shell companies secretly owned by officials at home. Unemployment is between 25 and 40 per cent. Inability to provide an adequate supply of electricity has been a notorious failing of the post-Saddam state, but the electricity ministry still managed to agree to pay $1.3bn to a bankrupt German company and a non-existent Canadian one. The government's budget is spent mainly on salaries and pensions, with recipients often connected to the ruling parties.
It is easy to be too pious about this. Most oil states in the Middle East and elsewhere use oil revenues to fund vast patronage machines and corruption is rife. But while bribery is pervasive in Iraqi Kurdistan, according to businessmen, roads, airports, bridges, power stations and houses get built there, while in Baghdad they do not. There are few banks and these are openly plundered by state officials. In the long run, continuing mass poverty and deprivation, despite soaring oil revenues, may be as destabilising to Iraq as sectarian differences between Sunni and Shia.
Disaster may come, but perhaps not yet. Iraqi politics can be misleading because, with the country so violent at the best of times, furious political confrontations do not necessarily lead to all-out conflict. Each side has a lot to lose from the final disintegration of the state.
The future of Iraq may well be decided in the capitals of its neighbours over the next year. The US remains important in Baghdad, despite the departure of its troops. The more divided Iraqis are, the more the influence of outside powers increases. Unfortunately, the Arab Spring has destabilised the whole Middle East, with Iran fearing it will lose its most important ally, Syria, while the Sunni-Shia struggle is becoming more intense in countries such as Bahrain.
Occasionally, Mr Maliki sounds like an Iraqi nationalist, but under pressure he plays the sectarian card, usually by frightening the Shias with the phantom of a Baathist and Sunni counter-revolution. But, as the Baathists and the Americans found to their cost, anybody who tries to monopolise power in Iraq, ignoring other power centres, creates the conditions for their own failure.