Khartoum is no friend of this fresh resolve on Darfur

The decision of the UN security council to authorise the deployment of a new peacekeeping force of 20,000 troops in Darfur is a positive step forward after four years of lethal inaction by the international community. Particularly welcome is the greater moral urgency brought to the issue by Gordon Brown and Nicolas Sarkozy, who co-sponsored the resolution and seem genuinely determined that it should live up to the secretary general's description of it as "historic and unprecedented". It won't bring back the estimated 400,000 killed so far, nor will it remove yet another appalling stain on the conscience of the world, but it could bring an end to the conflict that is still causing 7,000 deaths a month - provided, that is, the political will exists to implement it to the full.

This is an appropriate point at which to introduce a note of caution. I wonder how many of those excitedly announcing this "breakthrough" on our news bulletins were aware that the security council passed an almost identical resolution last August? It also called for a significant increase in the UN peacekeeping presence of more than 17,000 troops and, like the new resolution, mandated it to act under chapter 7 of the UN charter, using force where necessary to protect civilians from attack and ensure the delivery of aid supplies. It foundered, like many previous agreements, on the lack of international willpower and the obstructionism and bad faith of the Sudanese authorities. The force was never deployed.

Anyone assuming that this latest resolution has somehow fixed the problem should read the sobering analysis of it produced by Waging Peace, an NGO that has been calling for international action since 2004. It details a number of potential problems with the proposed UN force, from its truncated mandate to uncertainties about the robustness of its command and control arrangements. It is disappointing to note, for example, that the commitment to allow UN troops to seize illegal weapons in Darfur in last year's resolution has now been dropped, in favour of a weak monitoring role. There can be no long-term peace without disarmament, and that is not going to happen without serious pressure.

The main problem highlighted in the report - and one that is plain to anyone who has followed the tragedy of Darfur - is the cynicism and malevolence of the government in Khartoum. On each occasion that the UN has decided to act, Khartoum has professed a sincere intention to cooperate, only to throw up obstacles and objections when the focus of world attention has turned elsewhere. The programme of ethnic slaughter has then resumed as if nothing had changed. Sudan's leaders can do this because they know that the international community, until now, has lacked the leadership and attention span to remain consistently engaged. It is here that Brown and Sarkozy have the opportunity to make a real difference.

There are already signs that this gruesome cycle is in danger of being repeated. While the Sudanese ambassador to London was promising full compliance, his justice minister in Khartoum was describing the UN agreement as "stillborn". Expect more of the same in the weeks ahead, as the will of the UN is probed repeatedly for signs of weakness. The Sudanese will almost certainly return to a familiar tactic of objecting to the deployment of non-African peacekeepers, knowing perfectly well that without these the UN will be unable to find even half the troops needed for the job. We will only know that things have really changed when the UN insists on deploying regardless.

The fallacy at the heart of our failure in Darfur until now has been the idea that you can stop genocide and ethnic cleansing with the consent of those responsible. It's almost as if Bosnia never happened. That error persists even now, as the resolution describes the UN's "determination to work with the government of Sudan, in full respect of its sovereignty". There is no credible reason to believe that this noble sentiment is shared in Khartoum, and the sooner the international community realises that the better. Instead of treating the Sudanese government as a potential partner for peace, world leaders need to see it for what it is - a recalcitrant, criminal enterprise that will only yield when it is given no other choice.

The problem here does not lie with Brown or Sarkozy. They were obliged to water down their original draft in order to secure Chinese support, and in particular to take out references to the imposition of sanctions in the event of non-compliance. Indeed, there is evidence that both men appreciate what it will take to bring peace and justice to Darfur. It was particularly gratifying that Gordon Brown chose to make it clear in his speech to the UN before the vote that any attempt to block the new agreement would precipitate new sanctions. I hope he has already made contingency plans for this, because they will almost certainly be needed.

One option would be to increase direct pressure on the regime by extending travel bans and stepping up war crimes investigations against those responsible for orchestrating genocide. That would mean no more trips to London for "medical treatment" for Salah Gosh, the Sudanese intelligence chief listed as number two by a UN panel set up to identify war crimes suspects. The US has given red carpet treatment to the same man, on the implausible basis that he has useful information on Osama bin Laden, more than a decade after he left Khartoum. This gives the lie to the foolish notion that Sudan is on some neocon hit list. If only. At the other end of the spectrum must be a willingness to use coercive military force as a last resort. The next time Sudanese aircraft are used to murder defenceless civilians, French aircraft based in Chad, reinforced by the RAF, should be used to enforce the no-fly zone that is supposed to have been in place since 2004. A Franco-British operation could probably destroy Sudan's tiny inventory of ageing combat aircraft in a day. There would be no further need to police a no-fly zone, because there would be nothing left to fly.

What Darfur represents is an opportunity to develop a post-Iraq foreign policy in which the responsibility to protect is more than a glib soundbite or a cover for advancing power interests. The new leaders of Britain and France have made a good start. They now need to convert good intentions into determined action.

David Clark, a former Labour government adviser.