Moreover, traditional rivalries between Morocco and Algeria, and the unsolved question of Western Sahara's sovereignty, have blocked union meetings since the early 1990s despite several attempts to re-launch the political process. Western Sahara, a former Spanish colony south of Morocco that was "reintegrated" by the kingdom of Morocco, has declared independence as the Sahrawi Arab Democratic Republic. The latest top-level conference, in mid-2005, was derailed by Morocco's refusal to meet, due to Algeria's vocal support for Sahrawi independence. Algeria has continuously supported the Polisario Front liberation movement.