The 1978 South Lebanon conflict began after Israel invaded southern Lebanon up to the Litani River in March 1978, in response to the Coastal Road massacre near Tel Aviv by Lebanon-based Palestinian militants. The conflict resulted in the deaths of 1,100–2,000 Lebanese and Palestinians, 20 Israelis, and the internal displacement of 100,000 to 250,000 people in Lebanon. The Israel Defense Forces gained a military victory against the Palestine Liberation Organization as the latter was forced to withdraw from southern Lebanon, preventing it from launching attacks on Israel from across its land border with Lebanon. In response to the outbreak of hostilities, the United Nations Security Council adopted Resolution 425 and Resolution 426 on 19 March 1978, which called on Israel to immediately withdraw its troops from Lebanon and established the United Nations Interim Force in Lebanon (UNIFIL).

The Litani River, the classical Leontes, is an important water resource in southern Lebanon. The river rises in the fertile Beqaa Valley, west of Baalbek, and empties into the Mediterranean Sea north of Tyre. Exceeding 140 km in length, the Litani is the longest river in Lebanon and provides an average annual flow estimated at 920 million cubic meters. The waters of the Litani both originate and flow entirely within the borders of Lebanon. It provides a major source for water supply, irrigation and hydroelectricity both within Southern Lebanon, and the country as a whole.