 Complete the following phrase:  The Palestine Liberation Organization PLO recruited militants in Lebanon from among the Palestinian refugees who had been expelled or fled after the creation of Israel in 1948. After the PLO leadership and its Fatah brigade were expelled from Jordan in 197071 for fomenting a revolt, they entered Southern Lebanon, resulting in an increase of internal and cross-border violence. Meanwhile, demographic tensions over the Lebanese National Pact led to the Lebanese Civil War 19751990. PLO was one of the key factors to the eruption of the Lebanese Civil War and its bitter battles with Lebanese factions caused foreign intervention. Israels 1978 invasion of Lebanon pushed the PLO north of the Litani River, but the PLO continued their campaign against Israel. 