SUDAN has seldom received a foreign leader as it did Iran's President Hashemi Rafsanjani on Dec. 13. People poured into the streets carrying pictures of Imam Khomeini. This is unusual, since all the Muslims of the Sudan are Sunnis, while the Iranians are Shiites.The Sudanese went to the streets not to show warm feelings toward Iran, but to express rage against the way they have been treated as a result of their anti-United States stance in the Gulf crisis. It was a show of defiance against the policies of Egypt, Saudi Arabia, and their patron - the US. Since the Gulf war, Sudan has suffered economic devastation. Aid from Saudi Arabia and the Gulf states has stopped. This squeeze has added to the misery of a country already ravaged by a civil war between the Muslim north and the Christian south. The Sudanese have consequently embraced Iran as the symbol of resistance to US dominance. But an Iranian presence in Sudan would not only destabilize governments in the neighboring Arab states, it could also tend to destabilize much of the rest of Africa. To understand the full implications of Iran's influence in Sudan and its threat to regional stability, one has to look at it in light of these factors: (1) the collapse of communism has created an ideological vacuum in Africa and paved the road for the spread of Islamic fundamentalism; (2) the Egyptian government has abandoned its former "special relationship" with Sudan; and (3) Islamic movements in neighboring North African states such as Algeria and Tunisia are progressively gaining ground and credibi lity as an alternative to secular governments. Some analysts will see the political consequences of Iran's role in Sudan as similar to its role in Lebanon. But Iran's failure to gain a lasting foothold in Lebanon does not portent a similar failure in Sudan. For one thing, Lebanon's surrounding states, like Iraq and Syria, were strongly committed to a secular ideology. No such ideology exists in the African states that border Sudan. In fact, Islamic movements are gaining ground in Nigeria, Senegal, Mali, Tanzania, and the Ivory Coast. Second, an Iranian presence would destabilize the pro-American government in Egypt. According to conventional political wisdom, a strong Egyptian/Sudanese relationship stabilizes both governments. However, Egyptian President Hosni Mubarak's abandonment of this traditional role has created a vacuum in Sudan. Iran would like to fill it. THE Iranian revolution continues to send a powerful message to Islamic groups - that if the Muslims of Iran could defeat a strong ruler like the Shah, then other groups of believers could do likewise. It is that message that encouraged a groups of young Egyptians to assassinate Sadat. It is not out of the realm of possibility that the new Iranian presence in Egypt's backyard may encourage those who'd like to remove Mr. Mubarak. The conditions are ripe for such acts. The economy of Egypt is in shambles, especially after the return of millions of workers from the Gulf states. Moreover, Mubarak's opposition will seize any opportunity to exploit Egyptians' feelings concerning their ties with the Sudan. Historically, Egypt and Sudan have looked upon each other as one country. Egypt's policymakers have always considered Sudan as their strategic depth. Opposition leaders in Egypt such as Ibrahim Shukri are calling Mubarak's withdrawal of Egyptian support for the Sudan a blunder. Existing hostility between Egypt and Iran could intensify. During the Gulf crisis, some 2,000 Iranian revolutionary guards went to Sudan to help train the Islamic militias who volunteered to fight on the side of Iraq. These groups included many from Islamic groups in Egypt, who still remain in the Sudan. Third, a new Iranian presence in the Sudan is dangerous because it creates an atmosphere that connects the already established Islamic movements in Sudan, Algeria, and Tunisia. A united Islamic front under the leadership of Turabi in Sudan, Ghanouchi in Tunisia, and Madani in Algeria is a threat to the stability of neighboring states. Islamic movements are already very influential in Egypt, especially in southern Egypt which directly borders the Sudan and has long been economically neglected by the Cairo government. The southern city of Assiut has long been a center of fundamentalism. The Egyptian fundamentalists are Sunni, but despite this they have supported the Islamic revolution in Iran. The post Khomeini government in Iran, moreover, has sought to minimize the Sunni-Shiite division. Considering these factors, the new Iranian role in the Sudan may prove damaging to US policies in Africa as well as destabilizing to neighboring Arab states. Iran may play the role of an agitator by exploiting existing sources of conflict. Iran may pit the Muslims of North Sudan against the Christian of the south, just as it exploited the Christian/ Muslim conflict in Lebanon. It is also likely to exploit the Sudanese-Egyptian conflict over water. The Sudanese are already talking about building dams on the Nile. Still, one has to recognize that the Sudanese government has been forced to ally itself with Iran. Egypt and Saudi Arabia wanted to punish the Sudanese for their refusal to join the anti-Iraq coalition. But the economic squeeze has driven the Sudanese government to look for other trading partners to get energy resources and to feed its people. Iran was their only option.