Ba'athist Syria launched a military intervention in the Lebanese Civil War in 1976, one year after the breakout of the war, as Syrian Arab Armed Forces began supporting Maronite militias against the Palestine Liberation Organization (PLO) and leftist militias. Syria also raised a proxy militia of its own, the Palestine Liberation Army (PLA). Hafez al-Assad's primary objective was to suppress the rise of PLO and allied pro-Palestinian militias in Lebanon which toed a hardline stance against Israel; and the invasion received widespread rebuke in the Arab world.
The involvement was later legalized under the pretext of Arab Deterrent Force of the Arab League. In 1982, Syria battled Israel over control of Lebanon.