On 6 June 1982, the Israeli army invaded Lebanon in what it described as 'retaliation' for the attempted assassination of Israeli Ambassador Argov in London on 4 June. The invasion, soon dubbed "Operation Peace for Galilee," progressed rapidly. By 18 June 1982, Israel had surrounded the Palestine Liberation Organisation's (PLO) armed forces in the western part of the Lebanese capital. A cease-fire, mediated by United States Envoy Philip Habib, resulted in the PLO evacuation of Beirut on 1 September 1982.
On 11 September 1982, Israeli Defence Minister Ariel Sharon, the architect of the invasion, announced that "2,000 terrorists" had remained inside the Palestinian refugee camps around Beirut. On Wednesday 15 September, the day after the assassination of Israeli-allied Phalangist militia leader and Lebanese President-elect Bashir Gemayel, the Israeli army occupied West Beirut, "encircling and sealing" the camps of Sabra and Shatila, which were inhabited by Lebanese and Palestinian civilians. By mid-day on 15 September 1982, the refugee camps were entirely surrounded by Israeli tanks and soldiers, who installed checkpoints at strategic locations and crossroads around the camps in order to monitor the entry or exit of any person. During the late afternoon and evening of that day, the camps were shelled.
On 11 September 1982, Israeli Defence Minister Ariel Sharon, the architect of the invasion, announced that "2,000 terrorists" had remained inside the Palestinian refugee camps around Beirut. On Wednesday 15 September, the day after the assassination of Israeli-allied Phalangist militia leader and Lebanese President-elect Bashir Gemayel, the Israeli army occupied West Beirut, "encircling and sealing" the camps of Sabra and Shatila, which were inhabited by Lebanese and Palestinian civilians. By mid-day on 15 September 1982, the refugee camps were entirely surrounded by Israeli tanks and soldiers, who installed checkpoints at strategic locations and crossroads around the camps in order to monitor the entry or exit of any person. During the late afternoon and evening of that day, the camps were shelled.