Additional Palestinian refugees arrived after the 1967 Arab – Israeli War . Following their defeat in the Jordanian civil war , thousands of Palestinian militiamen regrouped in Lebanon , led by Yasser Arafat 's Palestine Liberation Organization , with the intention of replicating the modus operandi of attacking Israel from a politically and militarily weak neighbour . Starting in 1968 , Palestinian militants of various affiliations began to use southern Lebanon as a launching pad for attacks on Israel . Two of these attacks led to a watershed event in Lebanon 's inchoate civil war . In July 1968 , a faction of George Habash 's Popular Front for the Liberation of Palestine ( PFLP ) hijacked an Israeli El Al civilian plane en route to Algiers ; in December , two PFLP gunmen shot at an El Al plane in Athens , resulting in the death of an Israeli
shot at an El Al plane in Athens
El Al Flight 253 attack
History of Lebanon