The invasion has created a series of problems
It was a few weeks before the invasion of Iraq, three years ago. I was interviewing the Saudi Foreign Minister, Prince Saud al-Faisal, in the ballroom of a big hotel in Cairo.
Shrewd, amusing, bulky in his superb white robes, he described to me all the disasters he was certain would follow the invasion.
The US and British troops would be bogged down in Iraq for years. There would be civil war between Sunnis and Shias. The real beneficiary would be the government in Iran.
"And what do the Americans say when you tell them this," I asked? "They don't even listen," he said.
Over the last three years, from a ringside seat here in Baghdad, I have watched his predictions come true, stage by stage.
The first stage was the looting.
Iraqis have voted, but still have no government
As Saddam Hussein fled Baghdad, people started attacking every symbol of the old system, no matter how self-destructive that might be.
I saw crowds of people sacking a hospital, running out with bits of equipment which were useless to them, but essential to the running of the hospital.
At the information ministry, I watched them stripping the claddings from the walls and the underlay from the floors. The American soldiers outside did nothing to stop them. Sometimes they would fire in the air, but the looters scarcely even looked round.
Until then, most Iraqis had thought the US was all-powerful, and was there to help them. The perception started to change then and there.
For the next year, if you were careful, you could wander round Baghdad, and even drive to other parts of the country.
When we arrived for a tour of duty we travelled by road to Baghdad from Jordan, through places like Falluja, or else from Kuwait, past Nasiriya and Hilla. It was sometimes nerve-racking, but we always got through. Now there is no alternative to flying in.
The BBC, like most other news organisations, is based in the city centre, not inside the Green Zone. It still is, but now our bureau is protected like a fortress.
Everything in Iraq changed in April 2004, with the American onslaught on Falluja. The town is small, but it took a long time to subdue - and it never has been subdued entirely. The ferocity of the American attack angered a broad swathe of Iraqi opinion.
At the same time, against the advice of many Iraqi politicians, the Americans also took on the Shia cleric Moqtada al-Sadr.
After that, the towns and cities of central Iraq became markedly more dangerous. We started hearing more of the American acronym IED, or improvised explosive device (it simply means a bomb).
The Coalition Provisional Authority under the leadership of Paul Bremer handed over to an interim Iraqi administration in July 2004.
It made little difference: the corruption had already started, and people now realised that neither the coalition nor the Iraqi administration could do anything about the failing water, power and fuel supplies.
The next key moment was the election of January 2005. The violence dropped noticeably, as the insurgents saw the size of the turnout and felt the general enthusiasm, and waited to see if they could do a deal with the new government.
But there was no new government for a full three months. The politicians squabbled among themselves, and the moment passed. The violence soon returned to its former level.
By July of last year there was already talk of civil war. A referendum and another election followed, and an effective administration was as far away as ever. Four months after the December election, Iraq still has no government.
The insurgency is fading a little now. Fewer American, British and Iraqi troops are dying, and there are less frequent attacks on the Iraqi police.
Instead, easier targets present themselves. There is an all-out effort to provoke a civil war. The bombings of Shia shrines are always followed by the murder of individual Sunnis: sometimes dozens at a time.
There is a quiet movement of population, as people leave mixed areas and head for places where others like them live. Marriages between Sunnis and Shias used to be frequent; now they've dropped away to almost nothing.
A psychiatrist at one of the main hospitals in Baghdad told me that serious mental illness in Iraq in the past had affected fewer than 3% of the population. Now, he said, the figure was 17%.
Another psychiatrist told me that in the days of Saddam Hussein, his patients had shown the effects of living under a ferocious dictatorship: stress levels were very high.
Now, he said, most of his patients suffered from post-traumatic stress disorder. It's no longer the fear of violence and injury which troubles them, it's the daily reality of it.
While we were filming, someone fired a gun close by. I won't easily forget the terrified way some of the patients flinched.
Doing and undoing
Just over three years ago, when I interviewed the Saudi foreign minister, I asked him why he thought the US was determined to invade Iraq.
He said he had put the same question to Vice-President Dick Cheney. Mr Cheney had replied: "Because it's do-able."
It was. The trouble is, undoing the kind of damage the Saudi foreign minister foresaw is proving very hard indeed.
Do you agree with John Simpson's views? Where does Iraq go from here? Is Iraq heading for civil war?