The arrival of 3,500 US Marines in Helmand province of Afghanistan will be welcomed widely, not least by the 7,800 British troops stationed there, who, along with their Canadian allies, have borne the brunt of the fight against the Taleban. In military terms, that struggle has been a broadly encouraging one with UK Forces inflicting a far higher level of attrition on their foes than they have been forced to receive in return. The notion of an exclusively military solution to this conflict is, however, one that is at odds with Afghanistan's history. The best that arms can do is create the opportunity for reconstruction, which will allow this country to take its first steps towards modernity. Without some advance of this form, this mission will never end.

As we report today, the coming of the Americans offers Britain a chance to think again about its strategy in southern Afghanistan. Contrary to some of the stereotypes initially made in Iraq, it is the United States Army, radically reshaped by General David Petraeus and his associate, General Dan MacNeill, that has been notably successful at combining offensive operations on the ground with the building of roads, schools and hospitals that win the hearts and minds of the local population. In Helmand, by contrast, Britain has been impressive on the battlefield but the track record on the humanitarian front has been patchy. Although General MacNeill, the overall commander in Afghanistan, is too diplomatic to put it so bluntly, there are lessons that Britain should learn from the way in which the US military conducts business.

Much of this happened because Britain has sharply divided its efforts between the Ministry of Defence for warfare and the Department for International Development (DfID), which assumes charge of the humanitarian dimension. This is a division that works less well in practice than it might in theory. Culturally, DfID remains much happier at organising aid schemes in Africa than it is at dovetailing with the military in what is in essence a warzone.

Outsourcing this operation can only work smoothly if DfID comes to regard itself as a direct arm of British foreign policy and not a semi-detached entity more content in the company of worthy NGOs than squaddies. As this deficiency will not be remedied overnight, the military itself, like the American Army, will have to become more forcefully involved in the reconstruction endeavour.

If it can do that then, with the assistance of the marines, it should be possible to make the sort of progress in Helmand that has been witnessed in eastern Afghanistan. With the decision of Nicolas Sarkozy to deepen French commitment to this cause, Nato's credibility in this region, which had started to appear very fragile earlier in the year, can be reasserted. In one important respect, nonetheless, it is important that US thinking is recast on British lines rather than vica versa. Some in the American military have pressed for poppy fields to be sprayed as soon as possible. While this is in one sense understandable in sentiment, such an approach executed before Afghans have seen any social and economic benefits from the Nato intervention would be counter-productive. There is a real chance to do good in Helmand. The battle is being won, but we are a long way from securing the peace.