Sunni Islamic fundamentalists have posed the most sustained and serious threat to the Baath regime. The government referred to these militants as the Muslim Brethren or Brotherhood (Ikhwan al Muslimin), although this is a generic term describing a number of separate organizations. The most important groups included the Aleppo-based Islamic Liberation Movement, established in 1963; the Islamic Liberation Party, founded in Jordan in the 1950s; Shabab Muhammad (Muhammad's Youth); Jund Allah (God's Soldiers); and At Tali'a al Muqatila (The Fighting Vanguard), established by the late Marwan Hadid in Hamah in 1965 and led in 1987 by Adnan Uqlah. The At Tali'a al Muqatila group, which did not recognize the spiritual or political authority of the exiled veteran leader of Syria's Sunni fundamentalists, Issam al Attar, bore the brunt of the actual fighting against the regime. In the early 1980s, the Muslim Brethren staged repeated hit-and-run attacks against the Syrian regime and assassinated several hundred middle-level government officials and members of the security forces and about two dozen Soviet advisers. The armed conflict between the Muslim Brethren and the regime culminated in full-scale insurrection in Aleppo in 1980 and in Hamah in February 1982. The government responded to the Hamah revolt with brutal force, crushing the rebellion by killing between 10,000 and 25,000 civilians and leveling large parts of the city...

Government security forces tried to uproot the Muslim Brotherhood from Hamah and Aleppo in late March and early April 1981. A large-scale search operation resulted in the deaths of 200 to 300 people and the destruction of sections of both cities. Tight security measures were implemented; membership in the Muslim Brotherhood was made a capital offense, the use of motorcycles was banned in some cities (they were used by the Muslim Brotherhood in hit-and-run attacks), and under the guise of holding a general census, the Ministry of Interior ordered all citizens 14 years of age and older to obtain new identity cards. In addition, a series of political, economic, and social measures were aimed at improving the regime's image and gaining more popular support...

In February 1982, the Muslim Brotherhood ambushed government forces who were searching for dissidents in Hamah. Several thousand Syrian troops, supported by armor and artillery, moved into the city and crushed the insurgents during two weeks of bloodshed. When the fighting was over, perhaps as many as 10,000 to 25,000 people lay dead, including an estimated 1,000 soldiers. In addition, large sections of Hamah's old city were destroyed. This battle led to the establishment of the National Alliance for the Liberation of Syria, including the Muslim Brotherhood, the Islamic Front, the pro-Iraqi wing of the Baath party, and other independent political figures. The destruction of Hamah and the ruthlessness of Assad's measures apparently has had a chastening effect on Syria's estimated 30,000 Muslim Brotherhood sympathizers...

Following the Hamah uprising, extremist antiregime Muslim groups in Syria seemed fragmented and presented little threat to the Assad regime...

On the third anniversary of the Hamah rebellion in February 1985, the government announced an amnesty for Muslim Brotherhood members. About 500 of the Muslim Brethren were released from prison, and those who had fled abroad were encouraged to return to Syria. As a result of the amnesty many members of At Tali'a al Muqatila surrendered to government authorities...

The December 30, 1985, visit by King Hussein to Damascus marked the end of seven years of unremitting hostility between the two nations. In conformity with the Assad Doctrine, Jordan renounced "partial, separate, and direct talks with Israel" and issued an abject apology and admission of guilt for having harbored and supported anti-Syrian Muslim Brotherhood terrorists in the early 1980s.