The PLO was formed in 1964 as an umbrella body for a number of elements of the Palestinian resistance movement. Its main constituent force was Al Fatah (Movement for the Liberation of Palestine), whose head, Yasir Arafat, assumed control of the PLO in 1968. At the outbreak of the invasion of Lebanon in 1982, Al Fatah numbered 6,500 armed men organized into regular units. Another PLO faction was the Popular Front for the Liberation of Palestine (PFLP), ideologically close to the Soviet Union and led by a Christian, George Habash. The PFLP was bitterly opposed to compromise with Israel. Numbering about 1,500 adherents in 1982, it was responsible for some of the most deadly international terrorist actions against Israel and its supporters. Other leftist groups had splintered from the PFLP, including the Democratic Front for the Liberation of Palestine (DFLP), the Popular Front for the Liberation of Palestine-General Command (with ties to Syria and Libya), and the Palestine Liberation Front (Iraq-supported). The Palestine Liberation Army (PLA), numbering nearly 4,000 men in 1982, was established in 1964 as the military arm of the PLO. In practice, however, the Syrian general staff controlled the PLA's contingents of Palestinian troops and the Jordanian army controlled one brigade in Jordan. The Abu Nidal organization, an anti-Arafat group supported by Libya and Syria, was responsible for many terrorist actions in Western Europe and against pro-Arafat Palestinians.

Initially linked to Syria, Al Fatah came into its own after the June 1967 War, when the West Bank and the Gaza Strip fell under Israeli control. Palestinian refugees poured into Jordan, where the PLO established virtually autonomous enclaves, and from which it launched guerrilla raids. Israel's retaliation inflicted heavy damage within Jordan. The PLO refused demands from King Hussein that it cease operations and, in a sharp conflict with Jordanian forces in 1970 and 1971, was driven out of Jordan. Shifting its headquarters to Lebanon, the PLO adopted a more formal military structure, benefiting from an abundant flow of arms from other Arab nations. In spite of the danger of Israeli reprisals, the Lebanese government was forced to accept the independent political and military presence of the PLO in Lebanon.

Airliner hijackings had been an element in the PLO's strategy since 1967. In retaliation against an attack on an El Al airliner in Athens in 1968, Israel mounted a helicopter raid against the Beirut International Airport, destroying thirteen Arab-owned aircraft. A number of deadly terrorist incidents and guerrilla attacks against Israeli West Bank settlements occurred during the 1970s. In an attempt at hostage-taking, the Black September group, an extremist faction of Al Fatah, killed eleven Israeli athletes at the Munich Olympics in 1972. A climax in the terrorist campaign occurred in March 1978, when Al Fatah raiders landed on the Israeli coast south of Haifa, attacking a bus and cars on the Tel Aviv-Haifa highway. Thirty-five Israelis were killed and at least seventy-four were wounded. In reaction to t 1c6a the highway attack, the IDF launched Operation Litani in April 1978, a three-month expedition to clear the PLO guerrillas from Lebanese border areas. Within one week, the strong IDF force had driven back the PLO and established complete control in southern Lebanon up to the Litani River.

Nevertheless, the PLO had not been dealt a decisive blow. With Soviet help, it began to accumulate substantial numbers of heavy weapons, including long-range artillery, rocket launchers, antiaircraft weapons, and missiles. Between 1978 and 1981, numerous IDF raids against PLO installations in southern Lebanon were answered within hours by random artillery and rocket attacks on Israeli border settlements. By mid-1981, the reciprocal attacks were approaching the intensity of full-scale hostilities. Punishing bombing raids by the Israeli air force included an attack aimed at PLO headquarters in Beirut that caused many civilian casualties. Although a truce was arranged with the help of United States ambassador Philip Habib on July 24, 1981, acts of PLO terror did not abate inside Israel, in the West Bank, and in foreign countries. Israel considered the continued presence of long-range weapons threatening its northern population centers an unacceptable threat. In June 1982, Israel justified its invasion of Lebanon as the response to an assassination attempt against its ambassador in London by the Abu Nidal group. At the outset of the war, the PLO had approximately 15,000 organized forces and about 18,000 militia recruited among Palestinian refugees. In spite of the large quantity of weapons and armor it had acquired, it never reached the level of military competence needed to meet the IDF in regular combat. When three division-size IDF armored columns bore down on the 6,000 PLO fighters defending the coastal plain below Beirut, the Palestinians fought tenaciously even though they were poorly led and even abandoned by many senior officers. Effective resistance ended within a week when the IDF closed in on the Beirut suburbs (see 1982 Invasion of Lebanon, this ch.).

To avoid the domestic and international repercussions of the bloody street fighting that an attack on the PLO headquarters in West Beirut would have entailed, an agreement was negotiated whereby the PLO troops and command would evacuate Lebanon and withdraw to other Arab states willing to receive them. By September 1982, more than 14,000 PLO combatants had withdrawn. About 6,500 Al Fatah fighters sailed from Beirut. Most of the others crossed into Syria, and smaller contingents went to other Arab countries. As of 1987, it was believed that between 2,000 and 3,700 guerrillas were still in Syria, 2,000 were in Jordan, and smaller groups were quartered in Algeria, the Yemen Arab Republic (North Yemen), the People's Democratic Republic of Yemen (South Yemen), Iraq, Sudan, and Tunisia. By 1988, however, many PLO fighters had filtered back into Lebanon. About 3,000 armed men aligned with Al Fatah were located in two camps near Sidon, forty kilometers south of Beirut, and an additional 7,000 fighters aligned with Syria reportedly were deployed in bases and refugee camps in eastern and northern Lebanon.

Much of the Arab terrorism directed against Israel during the mid-to-late 1980s was conducted by Syrian-sponsored Palestinian groups that rejected Arafat. To a lesser extent, terrorist threats resulted from Libyan involvement or from Fatah and its Force 17. Terrorists made a number of attempts to infiltrate the Israeli coast by sea and the anti-Arafat Abu Musa faction mounted several terrorist attacks in Jerusalem. The Damascus-based PFLP waged a relentless campaign to inhibit the development of moderate Palestinian leadership in the occupied territories. The shadowy Abu Nidal was believed responsible for a number of actions in which Israel was not necessarily the primary target. These included the hijacking of an Egyptian airliner with the loss of many lives in late 1985, and shooting and grenade attacks at the El Al counters of the Rome and Vienna airports a few months later.

The Shia population of southern Lebanon had initially welcomed the IDF as adversaries of the PLO. By 1984, however, they had turned against the Israelis because of the dislocation caused by the Israeli occupation. Protests turned to violence in the form of hundreds of hit-and-run attacks by Shia gunmen against Israeli troops. The situation eased with the end of the Israeli occupation in mid-1985.

Southern Lebanon continued to be a potentially dangerous base for guerrilla attacks in 1988, following the partial reorganization of PLO elements in Lebanon and the introduction of hundreds of Shia radicals of the Hizballah (Party of God) movement supported by Iran. Numerous attempts had been made by terrorist squads to penetrate Israel's border defenses. A zone inside Lebanese territory eighty kilometers long and averaging ten kilometers in depth was patrolled by 1,000 IDF troops backed by 2,000 SLA militiamen recruited among Christian Maronites. The IDF conducted periodic sweeps of this zone to discourage cross-border infiltration and shelling by the PLO. The frontier itself was protected by antipersonnel mines, an electronic fence, acoustic, radar and night-vision systems, fortified positions, and mobile patrols.

The Palestinian uprising (intifadah) that broke out in December 1987 in the West Bank and Gaza Strip apparently was launched spontaneously and was not directly controlled by the PLO. Burying their longstanding rivalries, local members of Al Fatah, PFLP, DFLP, the Palestinian Communist Party, and fundamentalists of the Islamic Holy War faction provided leadership through "popular committees" in camps and villages. A loose coordinating body, the Unified National Command of the Uprising, distributed leaflets with guidance on the general lines of resistance. By August 1988, a separate Islamic fundamentalist organization had emerged. Known as Hamas, the Arabic acronym for a name that translates as the Islamic Resistance Movement, it rejected any political settlement with Israel, insisting that a solution would come only through a holy war (see Palestinian Uprising, December 1987- , this ch.).

Data as of December 1988