In earlier conflicts prior to the 1982 Israeli invasion, including Operation Litani, Israel attempted to eradicate PLO bases from Lebanon and support Christian Maronite militias. The 1982 invasion resulted in the PLO's departure from Lebanon. The creation of the Security Zone in South Lebanon benefited civilian Israelis, although at great cost to Palestinian and Lebanese civilians. Despite this Israeli success in eradicating PLO bases and its partial withdrawal in 1985, the Israeli invasion increased the severity of conflict with local Lebanese militias and resulted in the consolidation of several local Shia Muslim movements in Lebanon, including Hezbollah and Amal, from a previously unorganized guerrilla movement in the south. Over the years, military casualties of both sides grew higher, as both parties used more modern weaponry, and Hezbollah progressed in its tactics. By the early 1990s, Hezbollah, with support from Syria and Iran, emerged as the leading group and military power, monopolizing guerrilla activity in South Lebanon.