A joint United Nations-African Union force takes over peacekeeping operations in the Sudanese province of Darfur on Monday with barely a third of its planned 26,000 personnel deployed.

It is an inauspicious start to what was to have been the world’s largest peacekeeping operation, mandated to aid and protect the hundreds of thousands of civilians displaced in more than four years of conflict between the Khartoum government and its militia allies and Darfur rebel groups.