On March 23, 1978, following one of the earliest Israeli invasions of Lebanon, the first United Nations Interim Force in Lebanon (UNIFIL) arrived in the country to oversee the IDF withdrawal and monitor the situation. In the years since, the force has been extended annually and expanded a number of times as conflict between the two countries continues.On March 11 of that year, Palestinian terrorists based in Lebanon carried out the deadliest terror attack ever perpetrated in Israel – the Coastal Road Massacre. Launched by sea from southern Lebanon, Fatah terrorists landed in central Israel and began a shooting spree and bus hijacking that left 38 people dead and over 70 injured. Israel’s response to the Coastal Road Massacre came swiftly. Two days after the smoke cleared, then-prime minister Menachem Begin addressed the attack in a speech to the Knesset. Invoking Nazi imagery, he told the plenum, “Gone forever are the days when Jewish blood could be shed with impunity.” Hinting at what his government was planning for the very next day, he forewarned: “We shall do what has to be done.”Three days after the massacre, on March 14, some 25,000 IDF soldiers crossed the border into Lebanon with the stated goal of pushing the armed Palestinian groups to north of the Litani River. Before the Coastal Road terror attack, Palestinian groups had been shelling northern Israel for some time, but the massacre in central Israel was the clear impetus for the military offensive.The operation’s limited goals succeeded; PLO and other Palestinian armed groups retreated north of the Litani. The operation’s second goal, which it also temporarily accomplished, was to strengthen Israel’s ally in Lebanon at the time, the Maronite Christian Southern Lebanese Army (SLA).The international community, however, did not view the invasion favorably. Five days after the first Israeli infantry troops crossed the border, the United Nations Security Council passed two consecutive binding resolutions. The first, UNSC Resolution 425, called on Israel to cease its military activities in Lebanon and withdraw its forces from the country, and for the creation of an international interim force. The second resolution, UNSC Resolution 426, authorized the creation of UNIFIL. Four days later, the first UNIFIL troops arrived in southern Lebanon.Although Israel withdrew its forces from the country several months later in compliance with the UN resolutions, the conflict between the two adversaries was far from over and the role of UNIFIL was only beginning.Four years after UNIFIL’s initial deployment during Operation Litani, Israel once again invaded Lebanon in 1982, this time reaching further north into the capital, Beirut. Although that operation was eventually scaled back to holding only a buffer zone along the southern Lebanese border, the IDF remained on Lebanese soil for another 18 years until then-prime minister Ehud Barak initiated a full withdrawal from the country. The motivation for the withdrawal was two-fold. First, it aimed to render Hezbollah’s continued conflict with Israel as illegitimate by removing its claim to be liberating Lebanese territory from Israeli occupation. Second, the cost of holding the territory – both in blood and treasure – was high and domestic pressure on the government to end the bloody conflict had been building.However, until the Second Lebanon War in the summer of 2006, which came as a response to the kidnapping of two IDF reserve soldiers, UNIFIL’s role remained marginal. Its human cost was high – a number of international force members’ soldiers had been killed and kidnapped over the years – and its role largely constricted by rules of engagement that left it largely impotent.Following the Second Lebanon War, however, UNIFIL’s size and mandate were expanded. Under UNSC Resolution 1701, which officially ushered in the ceasefire that ended the war, UNIFIL was expanded to nearly 15,000 troops. The new mandate also charged it with overseeing the demilitarization of southern Lebanon and greatly expanded its rules of engagement, allowing it the freedom to not only defend itself but also civilians, UN personnel and facilities. The new authorization permitted taking “all the necessary action in areas of deployment of its forces, and as it deems with its capabilities, to ensure that its area of operations is not utilized for hostile activities of any kind.”Israel, however, has been consistently critical of the effectiveness of UNIFIL, since its creation and especially in its expanded role following the Second Lebanon War. Numerous politicians and leaders have described the mission as a failure for not stopping attacks against Israel from Lebanese territory. The Defense Ministry has accused the force of failing to stop arms shipments into southern Lebanon and in 2010, MK Shaul Mofaz said the mission had been incompetent in its failure to stop Hezbollah attacks against Israel.