Desmond Tutu writes: On what grounds do we decide that Robert Mugabe should go the International Criminal Court, Tony Blair should join the international speakers’ circuit, bin Laden should be assassinated, but Iraq should be invaded, not because it possesses weapons of mass destruction, as Mr Bush’s chief supporter, Mr Blair, confessed last week, but in order to get rid of Saddam Hussein?

The cost of the decision to rid Iraq of its by-all-accounts despotic and murderous leader has been staggering, beginning in Iraq itself. Last year, an average of 6.5 people died there each day in suicide attacks and vehicle bombs, according to the Iraqi Body Count project. More than 110,000 Iraqis have died in the conflict since 2003 and millions have been displaced. By the end of last year, nearly 4,500 American soldiers had been killed and more than 32,000 wounded.

On these grounds alone, in a consistent world, those responsible for this suffering and loss of life should be treading the same path as some of their African and Asian peers who have been made to answer for their actions in the Hague.

But even greater costs have been exacted beyond the killing fields, in the hardened hearts and minds of members of the human family across the world.

Has the potential for terrorist attacks decreased? To what extent have we succeeded in bringing the so-called Muslim and Judeo-Christian worlds closer together, in sowing the seeds of understanding and hope?

Leadership and morality are indivisible. Good leaders are the custodians of morality. The question is not whether Saddam Hussein was good or bad or how many of his people he massacred. The point is that Mr Bush and Mr Blair should not have allowed themselves to stoop to his immoral level.