After its forced withdrawal from Jordan in 1970, the Palestinian Liberation Organization (PLO) intensified its actions in Lebanon. As had been the case in Jordan, the presence of the armed guerrilla groups also led to conflicts in Lebanon. Israel promptly retaliated after each Palestinian guerrilla raid from Lebanese soil. In 1973, the PLO lost three of its leaders in an Israeli commando action in Beirut. In this case the Lebanese army also undertook action against Palestinian guerrilla bases and refugee camps.
In March 1978, in retaliation for another Palestinian raid in Israel in which dozens of civilians were killed, Israeli troops occupied the south of Lebanon, where a Civil War had raged between a ‘Christian Right’ and a ‘Muslim Left’ since 1975. The UN Security Council, ‘gravely concerned at the deterioration of the situation in the Middle East’, called upon Israel to withdraw its forces from Lebanon and created the United Nations Interim Force in Lebanon (UNIFIL). 4,000 UNIFIL soldiers, two months later increased to 6,000, were stationed in the south of Lebanon.
Paradoxically, Israel’s role in the conflict only increased in the following years. To begin with, it withdrew its forces from Lebanon, but retained control of an area in the south, manned by its ally, the Christian militia of Sad Haddad, called the South Lebanon Army (SLA).
In 1981, Israel bombed Beirut. A year later, in June 1982, in ‘retaliation’ for the murder of the Israeli ambassador in London, committed by the dissident Palestinian group of Abu Nidal (not by a PLO member organization), Israel started the operation ‘Peace for Galilee’ and invaded the country again. The Israeli troops now went as far as Beirut, laid siege to the Lebanese capital, crushed the Palestinian forces, and realized the departure of the PLO and most of its guerrilla fighters, who left for Tunis under international guarantees for their own safety and that of their dependents. Nevertheless, under the eye of the Israeli army, Christian militias entered the Palestinian refugee camps of Sabra and Shatila on the outskirts of Beirut and massacred hundreds of Palestinian civilians. The number of victims is estimated at about 2,000. The massacre brought about an international outcry. The Israeli Defence Minister at that time, the later Prime Minister Ariel Sharon, was forced to resign. Israel eventually withdrew its forces from Lebanon in June 1985, except for an 18 kilometres wide buffer zone along Lebanon’s southern border.