The Mountain War, also known as the War of the Mountain, was a subconflict between the 1982–83 phase of the Lebanese Civil War and the 1984–89 phase of the Lebanese Civil War, which occurred at the mountainous Chouf District located south-east of the Lebanese Capital Beirut. It pitted the Christian Lebanese Forces militia (LF) and the official Lebanese Armed Forces (LAF) against a coalition of the Druze Progressive Socialist Party (PSP) and the PNSF's Popular Front for the Liberation of Palestine – General Command (PFLP-GC), Fatah al-Intifada and As-Sa'iqa backed by Syria. Hostilities began when the LF and the LAF entered the predominantly Druze Chouf district to bring back the region under government control, only to be met with fierce resistance from local Druze militias and their allies. The PSP leader Walid Jumblatt's persistence to join the central government and his instigation of a wider opposition faction led to disintegration of the already fragile LAF and the eventual collapse of the government under President Amin Gemayel.

The Lebanese Civil War was a multifaceted armed conflict that took place from 1975 to 1990. It resulted in an estimated 150,000 fatalities and also led to the exodus of almost one million people from Lebanon.