The conflict over Western Sahara between the Kingdom of Morocco and the Polisario Front, a rebel movement striving for the independence of Western Sahara from Morocco, has been on the agenda of the UN Security Council since 1991. The settlement plan that came into effect that year envisaged a referendum on self-determination for the people of Western Sahara with the choice of either integration with Morocco or independence. This "win or lose" approach is responsible for the "take no prisoners," zero-sum attitude adopted by both sides ever since. It has caused both parties to miss opportunities for a solution that would have allowed each to get some of what it wanted while allowing the other to save face. It has also paralyzed the UN from taking decisive action that could have resolved the conflict.