A departure that betrays Mr Bush's dilemma over what to do next in Iraq

The resignation of a US under-secretary for defence does not often cause ripples, let alone waves, beyond the generous perimeter of the Pentagon. The resignation of Douglas Feith, however, is different. For Mr Feith is not just any US defence official; he is widely seen as a focus of the group that advocated, and then orchestrated, the invasion of Iraq. Specifically, he was responsible for making the intelligence-based case for war. A close associate of the so-called Prince of Darkness, Richard Perle, he could also be described as a founder member of the ideological clique known as the neoconservatives.

The resignation of a US under-secretary for defence does not often cause ripples, let alone waves, beyond the generous perimeter of the Pentagon. The resignation of Douglas Feith, however, is different. For Mr Feith is not just any US defence official; he is widely seen as a focus of the group that advocated, and then orchestrated, the invasion of Iraq. Specifically, he was responsible for making the intelligence-based case for war. A close associate of the so-called Prince of Darkness, Richard Perle, he could also be described as a founder member of the ideological clique known as the neoconservatives.

In other words, Mr Feith is a bigger fish than his job title might suggest. If it is also true that the Defence Secretary, Donald Rumsfeld, fought hard to keep him, there is but one conclusion to be drawn: the influence of the "neocons" inside the new Bush administration is not what it was. They are no longer capable of protecting their own. The more ideologically inclined among them - those whose departure would not be seized upon as an acknowledgement of major policy failure - are being quietly let go.

Mr Feith is not the only emblematic right-winger leaving the administration. His like-minded opposite number at the State Department, John Bolton, is not staying for Mr Bush's second term either. Mr Bolton's highly ideological approach and intemperate rhetoric had made him the butt of criticism among more moderate Republicans, and as the very public face of Mr Bush's aggressive post-11 September foreign policy, he became a positive liability in relations with Europe. One by one, it seems, the administration is ridding itself of those whose recommendation for the job was more ideological than professional.

The question, as so often with Mr Bush, is whether the external signs add up to a change in substance. Do these departures, and the more accommodating rhetoric employed recently in diplomatic statements, mean that the substance of foreign policy is set to change as well? The rhetorical adjustment is promising, suggesting as it does a greater willingness in Washington to listen to allies. At very least, it means that the White House is acknowledging the existence of a problem with US diplomacy as it evolved during Mr Bush's first term. Condoleezza Rice's professed openness to ideas, and her pledges on diversity when she took up her post as Secretary of State yesterday, were also encouraging.

The touchstone for any change, of course, will be Iraq, and the US approach to those of its allies who oppose the ill-conceived and mismanaged project to this day. Mr Bush has a dinner date with President Chirac in Brussels next month, and - another conciliatory gesture - meetings at EU headquarters, as well as Nato. Ahead, however, are disagreements on how to handle Iran's nuclear ambitions and the EU decision to lift its arms embargo on China. And it will take a masterly use of diplomatic language on both sides to smooth the ructions that either, or both, could cause.

In the end, the most compelling argument for change on Washington's part may be that it cannot be avoided. The White House confirmed this week that it would be asking Congress for an additional $80bn for operations in Afghanistan and Iraq - the combination disguising how much of a strain the Iraq war is exerting on the US budget. US public support for the war is waning; there is concern in the military about medical and pension costs, and how thinly reserves are being stretched.

Much will depend on the course of Iraq's elections this weekend, but the Pentagon is already talking about speedy hand-overs to regional Iraqi commanders in coming months. There is no open talk - yet - of cutting and running, but nor is there any evident strategy for leaving. No wonder, then, if the administration is seeking to replace its more starry-eyed dogmatists with practical executives and diplomats whose hard-line rhetoric will not alienate the allies.