Yemen was the only country in the Arabian Peninsula that was not a member of the GCC. Saudi Arabia had excluded Yemen (actually two separate countries, the Yemen Arab Republic, YAR, or North Yemen and the People's Democratic Republic of Yemen, PDRY, or South Yemen from 1962 until unification in 1990) from GCC membership because of its republican form of government. Historically, Saudi relations with Yemen had been problematic. In 1934 Abd al Aziz had sent his army into Yemen in an unsuccessful effort to conquer the country. Although the hereditary Shia ruling family of Yemen, concentrated in the north, never lost its distrust of the Al Saud, it accepted military assistance from Riyadh after it was deposed in a republican coup in 1962. For the next five years, the Saudis supported the Yemeni royalists in their unsuccessful struggle to regain control from the republican regime backed by Egypt. In November 1962, Cairo tried to intimidate Riyadh into withdrawing its support by sending Egyptian aircraft over southern Saudi Arabia to bomb several towns, including Abha where a hospital was hit and thirty-six patients were killed (see The Reigns of Saud and Faisal, 1953-75 , ch. 1). Following the June 1967 Arab-Israeli War, Saudi Arabia and Egypt resolved their differences over the YAR in practice this meant that Riyadh accepted the republican government in Sanaa. Relations gradually normalized by the late 1970s, Saudi Arabia was providing economic and military aid to the YAR. Nevertheless, the Saudis remained suspicious of their republican neighbor, and major outstanding issues such as the demarcation of borders were not addressed.

Saudi Arabia's attitude toward the PDRY influenced its overall Yemen policy. After Britain granted independence to its former colony of Aden and the adjoining protectorate of South Arabia in late 1967, a self-proclaimed Marxist government gained control of the entire area. Riyadh became preoccupied with containing the spread of Aden's Marxist ideas to the rest of the Arabian Peninsula, especially in Oman, where a PDRY-backed insurgency movement fought against the Al Bu Said Omani dynastic government during the late 1960s and early 1970s. Until 1976, when diplomatic relations with the PDRY were finally established, Saudi Arabia actively supported efforts to overthrow the regime in Aden Saudi hostility did not abate after 1976 but assumed more discreet forms, including covert aid to dissident factions within the ruling Yemeni Socialist Party (YSP). Opposition to the unification of the YAR and the PDRY also became a Saudi foreign policy objective, primarily because Riyadh feared the much disliked YSP would dominate a unified Yemen and thus acquire an even larger base from which to disseminate its radical ideas. When unification occurred in early 1990, the Saudis increased clandestine funding to various Yemeni groups opposed to the YSP.

Saudi Arabia's displeasure with Yemen's unification was mild compared with its reaction to Yemen's position in the Persian Gulf War. Yemen adopted a ne2b6 neutral stance, condemning the Iraqi invasion and annexation of Kuwait but refusing to support UN sanctions or the use of force. Yemen's policy incensed the Saudis, who terminated their economic assistance to the republic. In addition, Riyadh expelled about 1 million Yemeni workers who were residing in the kingdom in 1990. Relations between Saudi Arabia and Yemen remained strained in 1992.

Data as of December 1992