Morocco became a UN member on 12 November 1956 and participates in ECA and all the nonregional specialized agencies. The nation is a member of the African Development Bank, G-77, and the Arab League and is a signatory to the Law of the Sea. In recent decades, Morocco has pursued a policy of nonalignment and has sought and received aid from the United States, Western Europe, and the former USSR. Relations with Algeria and Libya have been tense, especially since Morocco's takeover of the Western Sahara. In 1988, UN Secretary General Perez de Cuellar negotiated with Morocco and Polisario (a group seeking sovereignty for the Western Sahara as the Saharan Arab Democratic Republic) to accept a cease-fire and to hold a referendum for the territory to determine whether it will be independent of integrate with Morocco. Although the vote was scheduled for 1992, it has been blocked by disagreements over voter eligibility, and sovereignty was unresolved as of 2003. Committed to the Arab cause in the Arab-Israeli conflict, Morocco sent troops to Syria in 1973. In 1989, Morocco restored relations with Algeria; it maintains relations with Saudi Arabia and the other Gulf states and condemned the Iraqi invasion of Kuwait.