The underlying tendency of the US over the next year seems likely to be one of drift and increasing weakness. A virtually lame-duck Bush administration will be carried by the current rather than shaping its own course. In many ways, this is of course preferable to the period of 2001-03, when the administration set out boldly to reshape the world, with disastrous results.

The problem, however, is that the stream ahead contains large rocks, on which American power, middle-eastern peace, and the world economy may all strike and founder. These rocks are not submerged – on the contrary they are in plain sight. But that does not mean that American policymakers will be able to avoid them.

In Iraq, American public opinion will, in my view, compel moves towards the progressive withdrawal of US forces from the frontline. Some will be withdrawn from Iraq altogether; others will be confined to bases, from where they will sally forth if the insurgents seem to be on the verge of winning major victories. As the Congressional elections of November 2006 approach, the pressure from Republican senators, congressmen and governors for a reduction of US casualties is likely to become irresistible.

The administration will seek to cover this with a flood of rhetoric about the Iraqis being ready to take over, but the reality will probably be increased power for US-armed Kurdish and Shi’a militia. This will ruin moves to bring the Sunni Arabs into the new political order, and point the country towards full-scale civil war. The implications of this for the region as a whole may well be disastrous, but will emerge in 2007 and after, rather than next year.

Two immediate threats are those of an Israeli attack on Iran’s nuclear sites – which would lead to various forms of violent Iranian retaliation – and a world economic crisis. Since one of the obvious potential catalysts for such a crisis is another oil shock stemming from market fears about the security of supplies from the Persian Gulf, it is easy to see how hitting the first rock could then lead to the US hitting the second. But given the deep weaknesses of America’s fiscal, debt and current account situation, an economic crisis could also be generated simply by structural factors in the US and world economies, as in 1929, rather than by a geopolitical event.

If – or perhaps rather when – such a crisis does strike, the key question will be whether the world’s leading economic powers will be capable of acting in unison to manage and contain it, or whether they will resort instead to some of the mutually destructive approaches adopted after 1929. If they fail, the political consequences across the world could be truly dire. But leading such an international response would require far greater vision than anything yet displayed by the Bush administration.