Since the 1970s there has been a cyclical pattern of guerrilla attacks carried out by Palestinian militiamen on Israel and by the IDF on Palestinian targets. In the aftermath of the 1975 Civil War, Lebanese-generated security concerns grew for Israel. At the same time, the breakdown of Lebanon's central government provided opportunities for Israel to act. Around 1975, Israel sponsored the creation of a surrogate force, Lebanese Christian (Melkite) Major Saad Haddad was the first officer to defect from the Lebanese Army to ally himself with Israel., a defection which led to the formation of the pro-Israel Free Lebanon Army, based in a corridor, the "Security Zone" along Lebanon's southern border from 1982 after Israel's invasion of Lebanon. This force, which called itself the Free Lebanon Army (but was later renamed the South Lebanon Army (SLA) under leader Antoine Lahad in May 1980), was intended to prevent infiltration into Israel of Palestinian guerrillas. In 1978, Israel invaded Lebanon, clearing out Palestine Liberation Organization (PLO) strongholds as far north as the Litani River.