The PLO in Lebanon and the Lebanese Civil War
Main article: Lebanese Civil War
In the mid-1970s, Arafat and his Fatah movement found themselves in a tenuous position politically. The PLO's Rejection Front opposed Arafat's growing calls for diplomacy from the mid-1970s, perhaps best symbolized by his support for a UN Security Council resolution proposed in 1976 calling for a two-state settlement on the pre-1967 borders and his Ten Points Program, which was denounced by the Rejection Front (and vetoed by the United States). The population in the Occupied Territories, for their part, saw Arafat as their only hope for a favourable resolution to the conflict, especially in the aftermath of the Camp David Accords, which Palestinians had seen as a blow to their aspirations to self-determination; on the other hand, Israeli leaders, who had their own designs for the Occupied Territories, resented Arafat's popularity and increasing diplomatic credibility. Meanwhile, Abu Nidal, a sworn enemy of the PLO since 1974, assassinated the PLO's diplomatic envoy to the European Economic Community, which in the Venice Declaration of 1980 had called for the Palestinian right of self-determination to be recognized by Israel. The sponsors of the assassination were never conclusively identified, but it was at any rate clear that Arafat's diplomatic machinations were not universally welcomed.
In the Lebanese Civil War the PLO first fought against the Maronites, then against Israel, then, finally, against the Syrian supported Amal militia. From 1985 to 1988 Amal besieged Palestinian refugee camps in Lebanon to drive out supporters of Arafat. Many thousands of Palestinians died of fire and starvation. After the Amal siege ended there was a great deal of intra-Palestinian fighting in the camps. (see War of the Camps)
Opposition to Arafat was notably fierce not only among radical Arab groups but among many on the Israeli right as well, including Menachem Begin, who had stated on more than one occasion that even if the PLO accepted UN Security Council resolution 242 and recognized Israel's right to exist, he would never negotiate with the organization (Smith, op. cit., p. 357). This contradicted the official United States position that it would negotiate with the PLO if the PLO accepted resolution 242 and recognized Israel, which the PLO had thus far been unwilling to do. Other Arab voices had recently called for a diplomatic resolution to the hostilities in accord with the international consensus, including Egyptian leader Anwar Sadat on his visit to Washington in August 1981 and Crown Prince Fahd of Saudi Arabia in his 7 August peace proposal; together with Arafat's diplomatic manoeuvres, these developments made Israel's argument that it had "no partner for peace" seem increasingly problematic. Thus, in the eyes of Israeli hard-liners, "the Palestinians posed a greater challenge to Israel as a peacemaking organization than as a military one" (Smith, op. cit., 376).
http://en.wikipedia.org/wiki/PLO#The_PLO_in_Lebanon_and_the_Lebanese_Civil_War