Despite a long history of hostility, between 1975 and 1977 Jordan's major regional ally was Syria. During 1975 Jordan and Syria agreed to coordinate their defense, foreign policy, economic, information, education, and cultural activities. They established a joint military command to provide a single defensive line against Israel. Syria halted anti-Hussein propaganda and imposed restrictions on Syrian-based Palestinian activities that might be considered prejudicial to Jordan's sovereignty.

The marked improvement in relations between Hussein and Syrian president Hafiz al Assad primarily reflected a shared desire to minimize the role of the PLO in any future Middle East peace negotiations. Despite the commitments made at Rabat, neither Jordan nor Syria wanted the PLO to emerge from Middle East peace talks as leader of a proposed Palestinian national entity in the occupied territories. Their opposition to the PLO, however, stemmed from very different sources. Jordan opposed the PLO because of conflicting territorial objectives Hussein wanted to reintegrate the West Bank as a part of a pre-1967 Jordan. Assad opposed a PLOled ministate because he feared that such an entity would reduce Syria's regional role and would significantly lessen the chances of Syria regaining the Golan Heights. At the same time, Damascus rejected Hussein's claims to the West Bank and vehemently opposed any Jordanian attempts to reach a separate peace agreement with Israel. This position severely limited the flexibility of Jordanian diplomacy and ultimately divided Jordan and Syria.

In 1975 Lebanon became engulfed in a bloody civil war that had major ramifications for the regional political balance. Like the Black September incident of 1970, the Lebanese Civil War pitted a rapidly expanding Palestinian political infrastructure against a sovereign Arab state. Between September 1970 and 1975, the Palestinians created in Lebanon a "state within a state." They had their own military establishment, an autonomous political structure, and separate collection of taxes. Unlike Jordan in 1970, however, Lebanon had a weak and badly divided political structure. As a result, in the spring of 1975, after a number of skirmishes with Lebanese Christian militias, the Palestinians allied with an array of leftist Lebanese forces and began an offensive. In the spring of 1976, it appeared that the Palestinians and their leftist allies would win the fighting. President Assad, fearing a radical Palestinian force on Syria's southern border, entered the fray on the side of the Christians and tilted the military balance in their favor. Jordan supported the Syrian intervention, fearing that a Palestinian victory would give the PLO a base of operations from which to destabilize the region.

Jordan's relationship with Syria also improved as Jordan became increasingly disenchanted with its relationship with the United States. Since the early 1970s, Jordan had negotiated for the purchase of a US$540 million air defense system from the United States to be financed by Saudi Arabia. When the United States Congress objected 417 d to the arms sale, Hussein commented that relations with his one-time sponsor had reached "a sad crossroads." In 1976, with Syrian encouragement, he traveled to Moscow to sound out the Soviet Union on its willingness to provide a similar system. In the face of persuasive American and Saudi lobbying, Hussein eventually opted to purchase the American Improved Hawk air defense system (see Military Cooperation with the United States , ch. 5). His trip to Moscow, however, marked a significant improvement in Jordanian-Soviet relations and was a factor in his decision to support the concept of a Middle East peace conference attended by both the Soviet Union and the United States.

Data as of December 1989