"I have fled twice in the past year," said Kassim Naji Salaman as he stood beside his petrol tanker outside the town of Khanaqin in central Iraq this weekend. "I and my family used to live in Baghdad but we ran for our lives when my uncle and nephew were killed and we moved into a house in the village of Kanaan in Diyala."
Mr Salaman hoped he and his family, all Sunni, would be safer in a Sunni district. But almost everywhere in Iraq is dangerous. "Militiamen kidnapped my brother Natik, who used to drive this tanker, and forced him into the boot of their car," he continued. "When they took him out they shot him in the head and left his body beside the road. I am frightened of going back to Kanaan where my family are refugees because the militiamen would kill me as well."
Iraqis expected their lives to get better when the US and Britain invaded with the intention of overthrowing Saddam Hussein four years ago today. They were divided on whether they were being liberated or occupied but almost no Iraqis fought for the old regime in 2003. Even his own Sunni community knew that Saddam had inflicted almost a quarter of a century of hot and cold war on his own people. He had reduced the standard of living of Iraqis, owners of vast oil reserves, from a level close to Greece to that of Mali.
No sooner had Saddam Hussein fallen than Iraqis were left in no doubt that they had been occupied not liberated. The army and security services were dissolved. As an independent state Iraq ceased to exist. "The Americans want clients not allies in Iraq," lamented one Iraqi dissident who had long lobbied for the invasion in London and Washington.
Guerrilla war against the US forces by the five million strong Sunni community erupted with extraordinary speed and ferocity. By summer 2003, whenever I went to the scene of a bomb attack or an ambush of US soldiers I would find jubilant Iraqis dancing for joy around the pools of drying blood on the road or the smouldering Humvee vehicles.
For Iraqis, every year has been worse than the last since 2003. In November and December last year alone 5,000 civilians were murdered, often tortured to death, according to the UN. This toll compares to 3,000 killed in 30 years of conflict in Northern Ireland. Many Iraqis have voted with their feet, some two million fleeing - mostly to Syria and Jordan - since President George Bush and Tony Blair ordered US and British troops across the Iraqi border four years ago today.
So dangerous is it to travel anywhere in Iraq outside Kurdistan that it is difficult for journalists to provide evidence of the slaughter house the country has become without being killed themselves. Mr Blair and Mr Bush have long implied that the violence is confined to central Iraq. This lie should have been permanently nailed by the Baker-Hamilton report written by senior Republicans and Democrats, which examined one day last summer when the US military had announced that there had been 93 attacks and discovered that the real figure was 1,100. In other words the violence was being understated by a factor of 10.
Diyala is one of the most violent provinces. It used to be one of the richest, with rich fruit orchards flourishing on the banks of the Diyala river before it joins the Tigris south of Baghdad. But its sectarian geography is lethal. Its population is a mixture of Sunni and Shia with a small Kurdish minority. For at least two years it has been convulsed by ever-escalating violence.
It is impossible for a foreign journalist to travel to Diyala from Baghdad unless he or she is embedded with the US forces. I knew, having made the journey before, that it was possible to get to Khanaqin, in the Kurdish controlled north-east corner of Diyala by taking a road passing through Kurdish villages along the Iraqi side of the Iranian border.
We started in Arbil, the Kurdish capital, and drove through the mountains to Sulaimaniyah three hours to the east. The Patriotic Union of Kurdistan (PUK), the party of Jalal Talabani, the Iraqi President, arranged a guide who knew the road to take us on to Khanaqin the following morning. We drove out of the mountains through the Derbendikan tunnel and then followed the right bank of the Diyala river, swollen by torrential rain, until we got to the tumble down town of Kalar. It is important here to turn right over a long bridge across the Diyala because the next town on the road, Jalawlah, is contested between Kurds and Arab Sunni. The road then goes in the direction of the Iranian border until it reaches Khanaqin, which is under PUK control.
We met a tribal leader from Jalawlah called Ghassim Mohammed Shati, who was also a police captain. He said: "The centre of the town is safe enough but my his father and brother and aunt were murdered on the outskirts in March 2005." Surprisingly Mr Shati did not favour shooting the insurgents who had killed his relatives. "The only solution is to give employment to the police and army officers who were sacked and now support al-Qa'ida. If they get jobs they will stop," he said. Everybody agreed the situation in Diyala was worse than ever. And the insurgents say they are setting up the Islamic emirate of Diyala.
Earlier this month the US, with much fanfare, sent 700 soldiers to Diyala to restore government authority. It fought a ferocious battle with insurgents in which it lost two armoured "Stryker" vehicles. But, as so often in Iraq, in the eyes of Iraqis the presence or absence of American forces does not make as much difference to who holds power locally as the US military command would like to believe. Supposedly they are supporting 20,000 Iraqi security forces, but earlier this year it was announced that 1,500 local police were to be fired for not opposing the insurgents. At one embarrassing moment US and Iraqi military commanders were claiming at a video-link press conference that they had a firm grip on the situation in Baquba when insurgents burst into the mayor's office, kidnapped him and blew it up.
Power in Diyala is fragmented. As in the rest of Iraq it is difficult to know who is in charge. The Iraqi government, whose ministers issue optimistic statements about the improving state of their country when on visits to London or Washington, carries surprisingly little weight outside the Green Zone in Baghdad. Often its interventions do nothing but harm. For instance the main source of employment in Khanaqin is the large border crossing from Iran at Monzariyah. Cross-border traffic provided 1,000 jobs. But the government has closed the crossing point and the road that used to be crowded with trucks a few months ago is now empty.
No rations, on which 60 per cent of Iraqis depend, have been delivered in Diyala for seven months. Those delivering them say it is too dangerous to do so since the drivers of trucks containing the rations are often deemed to be collaborators by insurgents and shot to death. In Mr Salaman's village of Kanaan, five men were burnt to death for guarding two petrol stations.
A difficulty in explaining Iraq to the outside world is that since 2003 the US and British governments have produced a series of spurious turning points. There was the capture of Saddam Hussein in December 2003, the supposed hand back of sovereignty in June 2004, the two elections and the new constitution in 2005 and - recently - the military "surge" into Baghdad. In all cases the benefits of these events were invented or exaggerated.
After Sunni fundamentalists blew up the golden-domed Shia al-Askari shrine in Samarra in February last year, central Iraq was torn apart by sectarian fighting. Baghdad broke up into a dozen hostile cities, Sunni and Shia, which fired mortars at each other. Government ministries, if controlled by different communities, fought each other. The Shia-controlled Interior Ministry kidnapped 150 people from the Sunni-held Higher Education Ministry and killed many of them.
For a brief moment last November, after the mid-term elections in the US and the Baker-Hamilton report, it seemed that the US was going to be start negotiations with its myriad enemies in around Iraq. But in the event President Bush refused to admit failure. Some 21,500 troop reinforcements are being sent to Baghdad and Anbar province to the west. So far there is little sign that the "surge" will really change the course of the war.
Diyala, its once-prosperous villages now becoming heavily armed Sunni or Shia fortresses, is a symbol of the failure of the occupation that began four years ago. From an early moment it was evident that only the Kurds in Iraq fully supported the US and British presence.
The invasion four years ago failed. It overthrew Saddam but did nothing more. It destabilised the Middle East. It tore apart Iraq. It was meant to show the world that the US was the world's only superpower that could do what it wanted. In fact it demonstrated that the US was weaker than the world supposed. The longer the US refuses to admit failure the longer the war will go on.