Israel's second invasion of Lebanon in June 1982 succeeded in driving thousands of Palestinian fighters under the command of PLO Chairman Yassir Arafat out of Southern Lebanon and West Beirut. Under international auspices, PLO forces were evacuated to northern Lebanon and re-settled in the port city of Tripoli. By this time, however, Syrian President Hafez al-Assad proceeded to expel Arafat and the Palestinian factions allied to him from Lebanon. Israel's 1982 invasion led to its beginning a 20-year-long occupation of a shallow fringe of southern Lebanon (10 to 15 kilometers) as a security zone for its border, allied with a local force - the South Lebanese Army, which was originally purely Christian but gradually added local Shiites and Druze to its ranks. Meanwhile, with permission from Syria, Iran sent a contingent of Revolutionary Guards to Lebanon, tasked with amalgamating, reorganizing and building up the small Shiite religious factions into a new organization - Hezbollah.