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.

[11][12] 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.

After the 2006 war the situation became relatively calm, despite both sides violating the ceasefire agreements; Israel by making near-daily flights over Lebanese territory, and Hezbollah by not disarming.

[22] The territories of what would become the states of Israel and Lebanon were once part of the Ottoman Empire which lasted from 1299 until its defeat in World War I and subsequent dissolution in 1922.

[24] Eventually, the resultant rise in ethnic tensions and violence between the Arabs and Jews due to Jewish immigration and collaboration would force the British to withdraw in 1947.

However, it was understood by all the state parties at the time that the armistice agreements were not peace treaties with Israel, nor the final resolution of the conflict between them, including the borders.

By 1949, there were 110,000 Palestinian Arabs in Lebanon,[31] moved into camps established by and administered by the United Nations Relief and Works Agency for Palestine Refugees in the Near East.

[32] Less democratic regimes also feared the threat the refugees posed to their own rule, but Lebanon would prove too weak to maintain a crackdown.

[11] The Palestine Liberation Organization (PLO) recruited militants in Lebanon from among the families of Palestinian refugees who had left Israel in 1948.

[11][12] Despite sharing in the ongoing border tensions over water,[33] Lebanon rejected calls by other Arab governments to participate in the 1967 Six-Day War.

[32] "The Palestinian resistance movement assumed daily management of the refugee camps, providing security as well as a wide variety of health, educational, and social services.

"[32] On 8 May 1970, a PLO faction, called the Democratic Front for the Liberation of Palestine, (DFLP) crossed into Israel and carried out the Avivim school bus massacre.

[39] The Popular Front for the Liberation of Palestine – General Command, which split from the PLO in 1974, carried out the Kiryat Shmona massacre in April of that year.

Changes in demographics and increased feelings of deprivation by certain ethnic groups, as well as Israeli–Palestinian clashes in the south of the county all contributed to the outbreak of the Lebanese Civil War.

[13] Beginning in May 1976, Israel supplied the Maronite militias, including the Lebanese Forces, led by Bachir Gemayel, with arms, tanks, and military advisers.

Fearing loss of commercial access to the port of Beirut, in June 1976 Syria intervened in the civil war to support the Maronite dominated government,[42] and by October had 40,000 troops stationed within Lebanon.

[43] In response, on 14 March 1978, Israel launched Operation Litani occupying southern Lebanon, except for the city of Tyre,[45] with 25,000 troops.

On 22 April 1979, Samir Kuntar and three other members of the Palestine Liberation Front, a sometimes faction of the PLO, landed in Nahariya, Israel from Tyre, Lebanon by boat.

The National Assembly of Lebanon narrowly chose Bachir Gemayel as president-elect, but when he was assassinated on 14 September 1982, Israel reoccupied West Beirut.

In August 1983, as Israel withdrew from the areas southeast of Beirut to the Awali River,[50] Lebanese factions clashed for control of the freed territory.

[51] On 15 January 1985, Israel adopted a phased withdrawal plan, finally retreating to the Litani River to form the 4–12 kilometers (2.5–7.5 miles) deep[41] Israeli Security Zone (map at[52]) while using the native South Lebanese Army militia to help control it.

[citation needed] On 16 February 1985, Shia Sheik Ibrahim al-Amin declared a manifesto[16] in Lebanon, announcing a resistance movement called Hezbollah, whose goals included combating the Israeli occupation.

The given reason was to retaliate for the death of IDF soldiers in the "security zone", which Israel had created in 1985 in southern Lebanon to protect its northern borders from both Hezbollah and the Popular Front for the Liberation of Palestine – General Command.

[54] On 11 April 1996, Israel initiated Operation Grapes of Wrath, known in Lebanon as the April War, which repeated the pattern of Operation Accountability.,[54] which was triggered by Hezbollah Katyusha rockets fired into Israel in response to the killing of two Lebanese by an IDF missile, and the killing of Lebanese boy by a road-side bomb.

The conflict ended on 26 April 1996 with the Israeli-Lebanese Ceasefire Understanding[55] in which both Hezbollah and Israel agreed to, respect the "rules of the game" and forgo attacks on civilians.

[56][57] The Israeli Air Force, in apparent response, on 7 February struck Lebanon's civilian infrastructure, including power stations at Baalbek, Deir Nbouh and Jambour.

On 10 June 2006, the Lebanese army arrested members of an alleged Israeli spy ring, including Mahmoud Rafeh, his wife, and two children.

[71] Heavy fire between the sides was exchanged across the length of the Blue Line, with Hezbollah targeting IDF positions near Israeli towns.

[134][135][136] On 2 January, Israel conducted an airstrike in the Dahieh neighborhood of Beirut, resulting in the assassination of Saleh al-Arouri, the deputy chairman of the Hamas political bureau.

[138] Since the civil war, Israel has routinely breached Lebanese airspace, waters, and borders, which is illegal since it violates Lebanon's territory and United Nations Security Council Resolution 425 and 1701.