Palestinian insurgency in South Lebanon in the context of "1982 Lebanon War"

The Israeli occupation of Southern Lebanon lasted for eighteen years, from 1982 until 2000. In June 1982, Israel invaded Lebanon in response to attacks from southern Lebanon by Palestinian militants. The Israel Defense Forces (IDF) occupied the southern half of Lebanon as far as the capital city Beirut, together with allied Maronite Christian paramilitaries involved in the Lebanese Civil War. The IDF left Beirut on 29 September 1982, but continued to occupy the country's southern half. Amid rising casualties from guerrilla attacks, the IDF withdrew south to the Awali river on 3 September 1983.

From February to April 1985, the IDF carried out a phased withdrawal to a "Security Zone" along the border, which it said was to protect northern Israel. From this point onwards, Israel supported the South Lebanon Army (SLA), the Lebanese Christian paramilitary, against Hezbollah and other Muslim militants. They fought a guerrilla war in Southern Lebanon throughout the occupation.

The United Nations Interim Force in Lebanon (Arabic: قوة الأمم المتحدة المؤقتة في لبنان; Hebrew: כוח האו"ם הזמני בלבנון), or UNIFIL (Arabic: يونيفيل; Hebrew: יוניפי״ל) is a United Nations peacekeeping mission established on 19 March 1978 by United Nations Security Council Resolutions 425 and 426, and several further resolutions in 2006 to confirm Hezbollah demilitarisation, support Lebanese army operations against insurgents and weapon smuggling, and confirming Israeli withdrawal from Lebanon, in order to ensure that the government of Lebanon would restore its effective authority in the area. The 1978 South Lebanon conflict came in the context of Palestinian insurgency in South Lebanon and the Lebanese Civil War.

The mandate had to be adjusted due to the Israeli invasion of Lebanon in 1982 and after the Israeli withdrawal from Lebanon in 2000. Following the 2006 Lebanon War, the United Nations Security Council enhanced UNIFIL and added additional tasks to the mandate such as aiding displaced persons.

United Nations Security Council Resolution 425, adopted on 19 March 1978, five days after the Israeli invasion of Lebanon in the context of Palestinian insurgency in South Lebanon and the Lebanese Civil War, called on Israel to withdraw immediately its forces from Lebanon and established the United Nations Interim Force In Lebanon (UNIFIL). It was adopted by 12 votes to none; Czechoslovakia and the Soviet Union abstained, and China did not participate.

The South Lebanon conflict was an armed conflict that took place in Israeli-occupied southern Lebanon from 1982 or 1985 until Israel's withdrawal in 2000. Hezbollah, along with other Shia Muslim and left-wing guerrillas, fought against Israel and its ally, the Catholic Christian-dominated South Lebanon Army (SLA). The SLA was supported militarily and logistically by the Israel Defense Forces (IDF) and operated under the jurisdiction of the Israeli-backed South Lebanon provisional administration, which succeeded the earlier Israeli-backed Free Lebanon State. Israel officially names the conflict the Security Zone in Lebanon Campaign and deems it to have begun on 30 September 1982, after the end of its "Operation Peace for Galilee". It can also be seen as an extension of the Lebanese Civil War (1975–1990).

Israel invaded Lebanon in 1978 and in 1982, to end the Palestinian insurgency in South Lebanon and support Lebanese Maronite Christians in the Lebanese Civil War. The 1982 invasion resulted in the Palestine Liberation Organization (PLO) leaving Lebanon and marked the beginning of Israeli occupation. Militant groups began attacking Israeli forces in southern Lebanon in September 1982. Amid rising casualties from guerrilla attacks, the IDF retreated south of the Awali river on 3 September 1983. The IDF began a phased withdrawal from Lebanon in February 1985. It withdrew to a "security zone" along the border on 29 April, and most IDF troops withdrew from the "security zone" on 10 June. A small number of IDF soldiers remained in the zone to support the SLA. Throughout its existence, there were about 1,500 IDF and 2,500 SLA troops in the "security zone" at any given time.

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).