Ongoing PLO terrorist activities against Israel from south Lebanon, where the organization had established itself after being expelled from Jordan in 1970, included rocket and artillery fire. Following an attack on Shlomo Argov, the Israeli ambassador to Britain, the First Lebanon War broke out.

Large IDF forces entered Lebanon and clashed with PLO terrorists and Syrian forces, which had been stationed there since the Lebanese Civil War. The objective of the war was to weaken the PLO terrorist units and force them away from south Lebanon, bringing peace to Israel's northern cities, towns and villages.

After almost three months of fighting, Israeli forces reached Beirut. In a United States-mediated agreement, Arafat and his men laid down their arms and left Lebanon for Tunis.                               

The consequences of the war:

The PLO in Lebanon was disbanded.

Hezbollah, which had been founded in response to the Israeli presence in Lebanon, entrenched itself and became stronger.

There were political debates inside Israel, especially in the wake of the Christian militia massacre in the Sabra and Shatila Palestinian refugee camps, and issues arose concerning captives and missing persons from Sultan Yacoub. The IDF presence in Lebanon lasted until 2000.

The Kahan Commission investigated the massacre and recommended that Ariel Sharon, the minister of defense, and Rafael Eitan the IDF chief of staff, both resign.