The Lebanon War – 1982

The Government of Israel launched the military operation after the Abu Nidal Organization's assassination attempt against Israel's ambassador to the United Kingdom, Shlomo Argov, which was used by Israel's Prime Minister Menachem Begin as justification for the invasion.

This justification for the Lebanon invasion by Israel has been criticized, given the 1974 split between the Abu Nidal Organisation and Arafat's PLO, that Abu Nidal was Arafat's mortal Palestinian enemy, that at the time its agents were also seeking to assassinate Fatah officials, and that it was based in Syria and not in Lebanon. 

By expelling the Palestine Liberation Organization (PLO), removing Syrian influence over Lebanon, and installing a pro-Israeli Christian government led by Bachir Gemayel, Israel hoped to sign a treaty which Menachem Begin promised would give Israel "forty years of peace". However, the long occupation that followed Israel's 1982 invasion had repercussions for Israel with Hezbollah being conceived to fight the Israeli occupation.

After attacking the PLO – as well as Syrian, leftist, and Muslim Lebanese forces – Israel occupied southern Lebanon, eventually surrounding the PLO and elements of the Syrian army. Surrounded in West Beirut and subjected to heavy bombardment, the PLO forces and their allies negotiated passage from Lebanon with the aid of United States Special Envoy Philip Habib and the protection of international peacekeepers. The PLO, under the chairmanship of Yasser Arafat, had relocated its headquarters to Tripoli in June 1982.

However, following the assassination of Lebanese President Bachir Gemayel, Israel's position in Beirut became untenable and the signing of a peace treaty became increasingly unlikely.

Outrage following Israel's role in the Phalangist-perpetrated Sabra and Shatila massacre, of mostly Palestinians and Lebanese Shiites, and Israeli popular disillusionment with the war would lead to a gradual withdrawal from Beirut to southern Lebanon, which was initiated following the 17 May Agreement and Syria's change of attitude towards the PLO. After Israel had left most of Lebanon, the War of the Camps broke out between Lebanese factions, the PLO and Syria, in which Syria fought its former Palestinian allies. At the same time, Shia militant groups began consolidating and waging a low-intensity guerrilla war over the Israeli occupation of southern Lebanon, leading to 18 years of low-scale armed conflict.