In the decades after the 1948 Arab-Israeli War, Israel's border with Lebanon remained relatively quiet compared to other borders. However, the situation changed following the 1969 Cairo Agreement, which allowed the Palestine Liberation Organization (PLO) to operate freely in South Lebanon, an area that became known as "Fatahland." The PLO, particularly its largest faction Fatah, frequently attacked Israel from this base, targeting towns like Kiryat Shmona. This lack of control over Palestinian groups was a key factor in triggering the Lebanese Civil War.

The attempted assassination of Israeli Ambassador Shlomo Argov in June 1982 served as a pretext for Israel to invade Lebanon, aiming to expel the PLO. Despite the Israeli cabinet authorizing only a limited incursion, Defense Minister Ariel Sharon and Chief of Staff Raphael Eitan expanded the operation deep into Lebanon, leading to the occupation of Beirut - the first Arab capital to be occupied by Israel. Initially, some Shia and Christian groups in South Lebanon welcomed the Israelis, having faced mistreatment by the PLO. However, over time, resentment towards the Israeli occupation grew, especially among the Shia community, which gradually radicalized under Iranian influence.^[212]

In August 1982, the PLO evacuated Lebanon, relocating to Tunisia. Shortly after, Bashir Gemayel, the newly elected President of Lebanon who reportedly agreed to recognize Israel and sign a peace treaty, was assassinated. Following his death, Phalangist Christian forces committed massacres in two Palestinian refugee camps. This led to massive protests in Israel, with up to 400,000 people demonstrating against the war in Tel Aviv. In 1983, an Israeli public inquiry found Ariel Sharon indirectly but personally responsible for the massacres, recommending that he never again hold the post of Defense Minister, although it did not preclude him from becoming Prime Minister.^[213]

The May 17 Agreement in 1983 between Israel and Lebanon was a step towards Israeli withdrawal, which occurred in stages until 1985. Israel continued operations against the PLO and maintained a presence in Southern Lebanon, supporting the South Lebanon Army until May 2000.