Few topics on the United Nations agenda have been as divisive within and even outside the organization as that of Western Sahara. The Western Sahara question has hung unresolved over the world body since the 1970s, when a rebellion broke out against Morocco's attempt to annex the territory in the wake of Spain's withdrawal. Morocco eventually secured control by force of arms, but the Polisario Front, sheltering in Algeria, remains a force to be reckoned with. The 1991 UN Settlement Plan for Western Sahara had laid out two possible but polar opposite outcomes that would follow a UN-supervised referendum on self-determination: either the territory would be integrated into Morocco, or it would become independent.