IN a vivid reminder of a country still riven by violence, insurgents marked yesterday's tenth anniversary of the invasion of Iraq with a co-ordinated series of car bombs in Baghdad that left around 50 dead and hundreds injured.

The invasion may have eclipsed Iraq's psychopathic dictator but it also destroyed the country's military, security and political structures, along with any hope of stability.

Today Iraq's very existence as a unified state hangs in the balance, as Prime Minister Nouri al-Maliki fights challenges from both the Kurds in the north and the Sunnis in the west.

Few of the many thousands who marched against the war in Glasgow and elsewhere in 2003 would deny that Saddam Hussein was an odious dictator, who had tortured and killed many of his own people. But, as The Herald argued at the time, that in itself was not a rationale for invading his country. Under international law, the aim of regime change per se is not a justification for war.

That is why the then Prime Minister Tony Blair laid so much store by his dossier, which purported to lay out evidence of the Iraqi dictator's weapons of mass destruction (WMD) and links to al-Qaeda. If neither of those claims held water, then Mr Blair and his ally George Bush were taking their countries into an illegal war on a false prospectus. So it has proved. It never seemed likely that al-Qaeda regarded Saddam as anything more than a degenerate despot. And it is now clear that heavy qualifications from MI6, CIA and other agencies around dubious and vague claims about WMD were omitted from the dossier. Contrary evidence was ignored. Either Mr Blair lied or, having committed himself privately to joining the US President in tackling Saddam, he somehow convinced himself that the evidence of the threat added up.

History will credit Mr Blair's governments with some impressive achievements, including the Good Friday agreement and lifting many households out of poverty, but the disaster of Iraq will forever define his premiership.

The cost will resonate for decades to come. The £10bn from the UK exchequer pales beside the lost lives of 179 service men and women, along with more than 3500 injured and thousands more who have lost their peace of mind as a result of what they saw in combat. The death toll in Iraq itself is closer to 100,000 and, despite the billions allocated for reconstruction, most has gone on military and security objectives, not the roads, utilities, schools and hospitals that are desperately required. Since 2000 Iraq has lost more than half its doctors.

In geopolitical terms too, the cost is incalculable: the fatal distraction from the conflict in Afghanistan, where the Taliban now lurks in the wings, waiting to grab power back the moment Nato leaves; the rise and rise of Iran to fill the power vacuum left by the disintegration of Iraq; and the discrediting of the whole philosophy of liberal interventionism to the point where the people of Syria have been left at the mercy of a regime every bit as ruthless as Saddam.

Iraq has damaged the UK's image abroad, especially in the Muslim world, and at home it has contributed to the erosion of trust in politicians in general. Few may mourn the passing of Saddam Hussein but in every other respect, this anniversary offers precious little to celebrate.