As a result of the Jordanian Civil War, the early 1970s saw a relocation of armed Palestinian groups, most notably the PLO, from Jordan into Lebanon, sharing a border with Israel. Tensions rose along this border due to PLO attacks against northern Israel and Israeli retaliatory strikes. Lebanon protested and the UN Security Council adopted Resolutions 425 and 426. This called for an immediate ceasefire and established UNIFIL to confirm the withdrawal of Israeli forces, restore peace and security, and assist the Lebanese government in restoring authority in the border area.
In 1982, violence erupted again after Israel invaded Lebanon, reaching and surrounding Beirut. UNIFIL’s role was limited to only providing civilian protection and humanitarian aid until Israel slowly began to withdraw in 1985. Following this détente, the situation in the area of UNIFIL operations remained generally quiet, but still tense. There were numerous violations of the withdrawal line, known as the “Blue Line”, but most were minor incidents.
In August 2010, after a clash between Israeli and Lebanese troops across the Blue Line, UNIFIL played an important role in mediation and peacekeeping. A UNFIL report determined that the cutting down of a tree, which had sparked the conflict, was on the Israeli side of the Blue Line, and that Lebanese snipers had therefore been unjustified in firing on Israeli positions. Since 2010, UNIFIL has continued to help ensure peaceful cross-border relations between the two states.New hostilities on the border began in July of 2006 when war erupted between the Shiite militant group Hezbollah and Israel. In August, after a ceasefire was reached, the UN decided to expand UNIFIL to conduct military observations and accompany and support the Lebanese armed forces, in order to help prevent a resurgence of conflict along the border.