Palestinian Crises:

Throughout the postwar period, there was increasing tension between the Maronites, who dominated the political scene and sought close ties with the west

A compromise was reached with the Cairo agreement of 1969, granting Palestinian militants (PLO) the right to keep weapons in their camps and attack Israel in the south, provided they respect Lebanese law and sovereignty.

In 1970, the PLO was expelled from Jordan after failing to topple King Hussein and established their main base in Lebanon

Hundreds of thousands of Palestinians entered the country, and the PLO, with about 23,000 troops, was now larger than the Lebanese army

The Lebanese National Movement (LNM) was founded and it was pro-PLO and opposed to what it perceived as excessive Maronite power.

Militant groups in Lebanon became stronger while thy Lebanon’s army remained weak.

The Syrian intervention:

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

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 

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. Syria claims these interventions came in response to appeals from Christian villagers under attack by Leftists in Lebanon.

Guerrilla warfare can be conceptualized under the broader term of low-intensity conflict (LIC), It is often protracted and ranges from diplomatic, economic, and psychological influences through insurgency and terrorist strategies.

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."[2]

In 1991, a Treaty of "Brotherhood, Cooperation, and Coordination", signed between Lebanon and Syria, legitimized the Syrian military presence in Lebanon.

Israel vs. PLO:  PLO started making mischief in southern Lebanon, prompting an Israeli invasion in

1978 Israel was supported by a break-away group of the Lebanese army composed of

Christians and Shias called South Lebanese Army. Israel withdrew in 1978, but left the SLA in charge of its security zone.

The war quickly moved into its next phase, marked by full-scale Israeli invasion in 1982. The excuse was the attempted assassination of the Israeli ambassador to the

UK by the PLO. The intention was to completely destroy the PLO and its infrastructure in Lebanon.

Given the tension between the PLO and the Shia in the south, the Israeli invasion, was initially welcomed by the Shia

Syria, was in fact against the Israel’s invasion because if it could penetrate southern Lebanon it could potentially attack Syria from two fronts.

The Israelis easily destroyed the Syrian air defense system. Israel reached Beirut and began a 70-day siege, bombarding the city in an attempt to wipe out the PL0.

What has been done to stop the civil war

TAIF aGGREMENT