Even those who thought they had become immune to such things have been shocked by last week’s carnage in Iraq. There’s been a flurry of diplomatic activity, prompted by a situation in which, as the BBC put it, “the statistics of murder and mayhem appear to break new records at disturbingly regular intervals.”

Yet the political class in the west still shies away from any rapid move to withdraw the occupying forces, even though this seems the course favoured by public opinion in both Iraq and the west. Even many who initially opposed the war have swallowed the line that leaving would make things worse.

But why would anyone believe that? Iraqi violence is shocking, but it is not random: it is still primarily framed by the occupation, and often directed against the occupiers and their perceived collaborators.

No-one should deny the possibility that things could get worse without US troops, but such a belief requires evidence rather than just assertion. The troops certainly don’t appear to be doing much to prevent a civil war, and the commonsense view is that they are actually inciting it. After all, many countries with equally deep and tangled ethnic/religious divisions manage to muddle through, with at worst low-level violence – look at Nigeria for example.

Without the occupiers, Iraqis will have no-one else to blame and will have to sort out their differences themselves. It may take much bloodshed before they do, but hypothetical future bloodshed is hardly a trump card against actual current bloodshed.

Supporters of the occupation demand that their opponents should first demonstrate that things would be better without the troops, but this is an absurd demand. Imagine applying it generally: you just pick a badly governed country – let’s say Belarus (already has NATO on its borders, so no need for ships) – walk in, kill lots of people, create chaos, and then demand proof that the Belarussians won’t be worse off on their own before leaving.

To call this a recipe for international anarchy would be too mild: it’s sheer madness. But Iraq has been a contagion of madness for far too long already.