The planned UN "peacekeeping" force for Darfur is destined to fail before it even arrives in a lawless land where up to 200,000 people have died and 10 times that number have become refugees in four years.

The inclusion of a handful of Western logistics experts and British officers with command experience means nothing when the bulk of the force is to be drawn from poorly trained, ill-disciplined and resource-starved African Union armies.

Some of the African Union troops from 26 states - already there in penny packets scattered across an area almost as big as France - have become part of the problem rather than the solution, with frequent accusations of looting and rape all too common. Like the UN fiascos in Rwanda and the Balkans, the decision to commit soldiers to Darfur is gesture politics - too little and far too late.

Even if the hostile Sudanese government had agreed to it, Britain lacks the military manpower to send anything other than a token contingent.

Committing transport aircraft may be a step too far as the Royal Air Force struggles to maintain air bridges to Afghanistan and Iraq.

The US, similarly overstretched, is also unable to contribute much more than supplies and platitudes.

While the UN grandly decrees the assembly of almost 20,000 soldiers and 6000 police officers for the task, the devil is in the detail of how the force will be made up and what authority it will be able to wield. There are already 7000 African Union soldiers in Darfur.

They have been there for three years and have not prevented a single massacre or dented the capability of the Janjaweed militias preying on local civilians. Part of the problem is the UN remit. Like the Blue Helmets in Bosnia, UN troops are not empowered to take the fight to the predators.

They have the right to respond to aggression only if it is aimed specifically at them or at refugees under their immediate care.

With 26,000 men to cover an area of almost 200,000 square miles, the chances of having enough troops in the right place at the right time is remote.

More to the point, to avoid annoying the Sudanese, the "peacekeepers" have no authority to disarm militias.