A narrow strip (3 to 9 miles wide) of land north of the Israel-Lebanon border retained by Israel following the unilateral withdrawal of most of the Israel Defense Forces (IDF) from Lebanon in the spring of 1985. The area was patrolled by small contingents of IDF soldiers and units of the Israeli-backed South Lebanese Army. The purpose of the security zone was to be a buffer to protect the towns and villages of northern Israel by keeping terrorists—such as the Palestine Liberation Organization and Hezbollah—out of Katyusha rocket range of the border region and by creating a physical barrier to terrorist incursions. However, the growing number of Israeli casualties in the security zone caused a heated public debate in the late 1990s about withdrawing IDF forces completely from the area. In the 1999 election campaign, One Israel leader Ehud Barak pledged to withdraw the IDF from the security zone within one year of becoming prime minister. That commitment was fulfilled on 24 May 2000. The United Nations certified that Israel met its obligations under United Nations Security Council Resolution 425 (1978) and had withdrawn fully from Lebanon.
Historical Dictionary of Israel. Bernard Reich David H. Goldberg. Edited by Jon Woronoff..