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Golan Heights published by the United Nations on 7 June 2000 for the purposes of determining whether Israel had fully withdrawn from Lebanon.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 130 kilometres (81 mi) 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.