The Syrian occupation of Lebanon began in 1976 as a result of the civil war and ended in April 2005 in response to domestic and international pressure after the assassination of former Lebanese Prime Minister, Rafik Hariri.
In January 1976, a Syrian proposal to restore the limits to the Palestinian guerrilla presence in Lebanon, which had been in place prior to the outbreak of the civil war, was welcomed by Maronites and conservative Muslims, but rejected by the Palestinian guerrillas and their Lebanese Druze-led and leftist allies. In June, 1976, To deal with the opposition posed by this latter group (which was normally allied with Syria), Syria dispatched Palestinian units under its control into Lebanon, and soon after sent in its own troops as well. Syrian claims these interventions came in response to appeals from Christian villagers under attack by Leftists in Lebanon.
By October 1976, Syria had caused significant damage to the strength of the Leftists and their Palestinian allies, but at a meeting of the Arab League, it was forced to accept a ceasefire. The League ministers decided to expand an existing small Arab peacekeeping force in Lebanon, but it grew to be a large Arab Deterrent Force consisting almost entirely of Syrian troops. The Syrian military intervention was thus legitimized and received subsidies from the Arab League for its activities.
Analyzing whether and when the Syrian presence was a military occupation under international law, Gerhard von Glahn claimed that the mandate of the Force was renewed several times before it officially expired on July 27, 1982. The Lebanese government refused to request that the mandate be renewed by the Arab League and instead, in September 1986, Lebanon actually requested an end to the Syrian presence in Lebanon. Hence, according to von Glahn, it appeared that lacking legal authority from both Lebanon and the Arab League, Syria's military forces had to be regarded henceforth as illegal occupants of Lebanon."
In 1989, at the final accords of the civil war, two rival administrations were formed in Lebanon: a military one under Aoun in East Beirut and a civilian one under Selim el-Hoss based in West Beirut; the latter gained the support of the Syrians. Aoun opposed the Syrian presence in Lebanon, citing the 1982 UN Security Council Resolution 520. In the resulting "War of Liberation", which erupted in March 1989, Aoun's forces were defeated and he himself exiled from Lebanon. In 1991, a Treaty of "Brotherhood, Cooperation, and Coordination", signed between Lebanon and Syria, legitimized the Syrian military presence in Lebanon. It stipulated that Lebanon would not be made a threat to Syria's security and that Syria was responsible for protecting Lebanon from external threats. In September that same year a Defense and Security Pact was enacted between the two countries.
Following the assassination of the Lebanese ex-premier Rafik Hariri in 2005, and an alleged involvement of Syria in his death a public uprising nicknamed Cedar Revolution had swept the country. With the consequent adoption of UN resolution 1559, Syria was forced to announce its full withdrawal from Lebanon on April 30, 2005.
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