What happened in 1982?

Using Lebanon as a base, Palestinian fighters mounted intermittent cross-border attacks against civilian and military targets in Israel. There were also international terrorist spectaculars, e.g., the 1972 Munich Olympics massacre, perpetrated by groups based in Lebanon. In turn, the Israelis struck back at targets and groups across the border in Lebanon from time to time.After the March 11, 1978 Bus Hijacking on the Coastal Road, Israel launched a major military incursion into South Lebanon, called the Litani River Operation. Israel crossed into southern Lebanon on March 15 and struck at PLO terrorist bases and staging areas south of the Litani