The Blue Line is a demarcation line between Lebanon and Israel and Lebanon and the Golan Heights published by the United Nations on 7 June 2000 for the purposes of determining whether Israel had fully withdrawn from Lebanon. It has been described as: "temporary" and "not a border, but a “line of withdrawal”. On 19 March 1978, the United Nations Security Council adopted Resolutions 425 and 426 calling for Israeli withdrawal from Lebanon following its recent invasion and to ensure that the government of Lebanon restores effective authority in the area to the border. The United Nations Security Council and NATO set up the United Nations Interim Force in Lebanon (UNIFIL) as a peacekeeping force to supervise the situation in Southern Lebanon. By September 2018 Israel completed 11 kilometers of a concrete Israel-Lebanon barrier on the Israeli side of the demarcation line to protect Israeli communities from infiltration by Hezbollah militants. The length of the barrier is to be and was expected to be complete by 2020. The project was expected to cost $450 million. Most of the barrier is a concrete wall topped by steel mesh, sensors and surveillance cameras. Steel fencing was to be used instead of concrete in especially rugged areas. The Blue Line On 11 March 1978 Palestine Liberation Organization (PLO) operatives, led by Dalal Mugrabi, carried out the Coastal Road massacre within Israel which resulted in the deaths of 37 Israelis, including 13 children, and 76 wounded. In response, Israeli forces invaded southern Lebanon from which the PLO operated regularly during the 1970s. Starting on the night of March 14–15 and culminating a few days later, Israel Defense Forces (IDF) troops occupied the entire southern part of the country except for the city of Tyre and its surrounding area. This operation is known in Israel as Operation Litani, the stated objective of which was to clear out PLO bases in Lebanon south of the Litani River, in order to better secure northern Israel and to support the Christian Lebanese militias in the course of the Lebanese Civil War - most notably the Free Lebanon Army. On 15 March 1978 the Lebanese government submitted a strong protest to the United Nations Security Council against the Israeli invasion, stating that it had no connection with the Palestinian operation. On 19 March 1978 the Council adopted Resolution 425, in which it called upon Israel to cease immediately its