in 1991). In October 1984, he renewed the treaty of Friendship and Cooperation that was originally signed in 1964 by San'a and Moscow. In February 1989, North Yemen joined Iraq, Jordan, and Egypt informing the Arab Cooperation Council (ACC), an organization created partly in response to the founding of the Gulf Cooperation Council, and intended to foster closer economic cooperation and integration among its members. After unification, the Republic of Yemen was accepted as a member of the ACC in place of its YAR predecessor. In the wake of the Persian Gulf crisis, the ACC has remained inactive. South Yemen British authorities left South Yemen in November 1967 in the wake of an intense resistance campaign. The People's Democratic Republic of Yemen, the successor to British colonial rule, had diplomatic relations with many nations, but its major links were with the Soviet Union and other Communist countries. Relations between it and the conservative Arab states of the Arabian Peninsula were strained. There were military clashes with Saudi Arabia in 1969 and 1973, and the PDRY provided active support for the Dhofar Rebellion against the Sultanate of Oman. The PDRY was the only Arab state to vote against admitting new Arab states from the Persian Gulf area to the United Nations and the Arab League. The PDRY provided sanctuary and material support to various international terrorist groups. Unified Yemen The Persian Gulf crisis dramatically affected Yemen's foreign relations. As a member of the UN Security Council (UNSC) for 1990 and 1991, Yemen abstained on a number of UNSC resolutions concerning Iraq and Kuwait and voted against the "use of force resolution". Western and Persian Gulf Arab states reacted by curtailing or canceling aid programs and diplomatic contacts. At least 850,000 Yemenis returned from Saudi Arabia and the Persian Gulf. After the liberation of Kuwait, Yemen continued to maintain high-level contacts with Iraq. This hampered its efforts to rejoin the Arab mainstream and to mend fences with its immediate neighbors. In 1993, Yemen launched an unsuccessful diplomatic offensive to restore relations with its Persian Gulf neighbors. Some of its aggrieved neighbors actively aided the south during the 1994 civil war. Since the end of that conflict, tangible progress has been made on the diplomatic front in restoring normal relations with Yemen's neighbors. The Omani-Yemeni border has been officially demarcated. In the summer of 2000, Yemen and Saudi Arabia signed an International Border