United Nations Interim Force in Lebanon in the context of "Blue Line (Lebanon)"

The Blue Line is a demarcation line dividing Lebanon from Israel and the Golan Heights. It was published by the United Nations on 7 June 2000 for the purposes of determining whether Israel had fully withdrawn from Lebanon.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”. It is the subject of an ongoing border dispute between Israel, Lebanon, and Hezbollah.

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.

An-Naqoura (Arabic: الناقورة, Enn Nâqoura, Naqoura, An Nāqūrah) is a municipality in southern Lebanon. Since March 23, 1978, the United Nations Interim Force in Lebanon (UNIFIL) has been headquartered in An-Naqoura.

United Nations Security Council Resolution 426, adopted on 19 March 1978 at the 2075th meeting of the Security Council, is concerned with both the creation of the United Nations Interim Force in Lebanon (UNIFIL) and the duration of its mandate. It comes immediately after and complements Resolution 425, adopted during an earlier meeting on the same day.

The resolution was adopted by 12 votes to none; Czechoslovakia and the Soviet Union abstained and the People's Republic of China did not participate in voting.

The 1978 South Lebanon conflict, also known as the First Israeli invasion of Lebanon and codenamed Operation Litani by Israel, began when Israel invaded southern Lebanon up to the Litani River in March 1978. It was in response to the Coastal Road massacre near Tel Aviv by Palestinian militants based in Lebanon. The conflict resulted in the deaths of 1,100–2,000 Lebanese and Palestinians, 20 Israelis, and the internal displacement of 100,000 to 250,000 people in Lebanon. The Israel Defense Forces gained a military victory against the Palestine Liberation Organization (PLO) as the latter was forced to withdraw from southern Lebanon, preventing it from launching attacks on Israel from across its land border with Lebanon. In response to the outbreak of hostilities, the United Nations Security Council adopted Resolution 425 and Resolution 426 on 19 March 1978, which called on Israel to immediately withdraw its troops from Lebanon and established the United Nations Interim Force in Lebanon (UNIFIL).

Israel launched a second invasion of Lebanon in 1982.

The Israeli–Lebanese conflict, or the South Lebanon conflict, is a long-running conflict involving Israel, Lebanon-based paramilitary groups, and sometimes Syria. The conflict peaked during the Lebanese Civil War. In response to Palestinian attacks from Lebanon, Israel invaded the country in 1978 and again in 1982. After this it occupied southern Lebanon until 2000, while fighting a guerrilla conflict against Shia paramilitaries. After Israel's withdrawal, Hezbollah attacks sparked the 2006 Lebanon War. A new period of conflict began in 2023, leading to the 2024 Israeli invasion of Lebanon.

The Palestine Liberation Organization (PLO) recruited militants in Lebanon from among the Palestinian refugees who had been expelled or fled after the creation of Israel in 1948. After the PLO leadership and its Fatah brigade were expelled from Jordan in 1970–71 for fomenting a revolt, they entered southern Lebanon, resulting in an increase of internal and cross-border violence. Meanwhile, demographic tensions over the Lebanese National Pact led to the Lebanese Civil War (1975–1990). PLO actions were one of the key factors in the eruption of the Lebanese Civil War and its bitter battles with Lebanese factions caused foreign intervention. Israel's 1978 invasion of Lebanon pushed the PLO north of the Litani River, but the PLO continued their campaign against Israel. This invasion led to the deployment of United Nations peacekeepers in southern Lebanon. Israel invaded Lebanon again in 1982 and, in alliance with the Christian Lebanese Forces, forcibly expelled the PLO. In 1983, Israel and Lebanon signed the May 17 Agreement providing a framework for the establishment of normal bilateral relations between the two countries, but relations were disrupted with takeover of Shia and Druze militias in early 1984. Israel withdrew from most of Lebanon in 1985, but kept control of a 19-kilometre (12-mile) security buffer zone, held with the aid of proxy militants in the South Lebanon Army (SLA).