November 1969: Lebanese army commander in chief Emile Bustani and Arafat sign an agreement in Cairo that recognizes the "Palestinian revolution" and allows Palestinians in Lebanon "to join in the armed struggle without undermining Lebanon's sovereignty and welfare." This agreement will stay in effect for nearly 20 years, until Lebanon rescinds it in May 1987.

1970-1971: Faced with fighting in Jordan that left thousands dead, the PLO moves its base to Lebanon, where it carries out raids on Israel. A Palestinian terrorist group linked to the PLO is formed. Its name is "Black September" -- a reference to the Jordanian crackdown on Palestinians in September 1970.

1972: Black September attacks the Israeli Olympic team during the games in Munich, Germany. After a struggle that left a coach and an athlete dead, the terrorists take nine Israeli athletes hostage, demanding the release of Palestinian prisoners in return for the hostages' release. Israel refuses, and a shootout between the attackers and West German authorities leaves all nine hostages, four terrorists and a policeman dead.

April 1973: Israeli elite commandos -- dressed as women and led by future Israeli Prime Minister Ehud Barak -- kill three PLO leaders in Beirut.

1975: Civil war breaks out in Lebanon, pitting Palestinians and pro-Palestinian Lebanese militias against Lebanon's Christian militias. The war would last nearly 15 years, officially ending in 1990.

1976: Syria sends military peacekeepers during the early months of the civil war to help end it. The troops would remain there nearly 30 years, until April 2005.

March 1978: A PLO attack on a bus in northern Israel prompts Israeli military forces to move into Lebanon to push the PLO back from the border. Israel withdraws after the U.N. Security Council passes a resolution for the immediate withdrawal of Israeli forces. Under the leadership of Lebanese army Maj. Saad Haddad, an Israeli ally, a 12-mile wide "security zone" is established to protect Israeli territory from cross-border attacks.

September 1978: The Camp David Accords, brokered by U.S. President Jimmy Carter, lead to a peace treaty between Israel and Egypt. The accords lay the groundwork for a similar treaty between Israel and Lebanon, as well as its other Arab neighbors.

July 17, 1981: Israeli forces bomb PLO headquarters in West Beirut, killing more than 300 civilians. The attack leads to a U.S.-brokered cease-fire between Israel, the PLO and Syria, whose troops were in Lebanon.

1982: The cease-fire lasts until June 6, 1982, when Israel invades Lebanon with about 60,000 troops in a push to destroy the PLO, after an assassination attempt on Israel's ambassador to Britain. Arafat and the PLO flee Lebanon in August and settle in Tunis, Tunisia, where they remain until moving to Gaza in 1994.

The Israel-backed Lebanese president-elect, Bashir Gemayel, is assassinated September 14, shortly before his inauguration. Israeli troops enter West Beirut a day later, and the following day, nearly 800 Palestinian refugees are massacred at the hands of Lebanese Christian militias in the Sabra and Shatila camps. Israel is accused of doing nothing to prevent or stop the massacre.

Hezbollah, a fundamentalist Shiite Muslim militant group, emerges as a force in Beirut, the Bekaa Valley and southern Lebanon. Sponsored by Iran, modeled after Iran's Revolutionary Guards and supported by Syria, Hezbollah aims to establish a Shiite Islamic state in Lebanon and force Western interests like Israel and the United States out of the region.

April 18, 1983: A suicide attack by Hezbollah on the U.S. Embassy in West Beirut kills 63 people, a harbinger of future attacks against U.S. and Western interests.

May 17, 1983: Lebanon and Israel sign a U.S.-brokered peace agreement, spelling out terms of Israeli withdrawal from Lebanon, conditional on the withdrawal of Syrian forces. Syria opposes the agreement.

October 23, 1983: A Hezbollah suicide bomber blows up the headquarters of U.S. Marine and French forces in Beirut, killing 298 people -- 241 of them U.S. Marines and other military personnel. U.S. troops are withdrawn from Lebanon a few months later.

January 18, 1984: American University of Beirut President Malcolm Kerr is assassinated.

March 1984: With pressure mounting from Syria, Lebanon cancels the May 17, 1983, peace agreement.

September 20, 1984: The U.S. Embassy annex in East Beirut is bombed, and 23 people are killed.

June 1985: Israel withdraws from most of Lebanon but keeps control of the 12-mile-wide security zone in the south. Israel remains there until May 2000.

1990: Lebanon's 15-year civil war officially ends.

July 1993: Israel attacks southern Lebanon in a weeklong operation aimed at ending Hezbollah attacks on Israeli towns.

April 1996: Israel and Hezbollah militants engage in a 16-day battle, in which at least 137 people, mostly Lebanese civilians, are killed.

May 2000: Israeli troops withdraw from southern Lebanon, and the United Nations establishes the "Blue Line" as a border between the two countries.

September 2003: Israeli warplanes hit southern Lebanon in response to Hezbollah's firing antiaircraft missiles at Israeli planes in the area.

October 2003: Israel and Lebanon exchange gunfire in the disputed area known as Shebaa Farms.

February 14, 2005: Former Lebanese Prime Minister Rafik Hariri is assassinated. Pressure builds on Syria to withdraw its remaining troops from Lebanon, which it does in April.

July 2006: Hezbollah militants cross into Israel, kill three Israeli soldiers and kidnap two others in a bid to negotiate a prisoner exchange, a demand rebuffed by Israel. Another five Israeli soldiers are killed after the ambush. Israel responds with a naval blockade and by bombing hundreds of targets in Lebanon, including Beirut's airport and Hezbollah's headquarters in southern Beirut. Hezbollah responds with rocket attacks targeting northern Israeli cities. Fighting leaves dozens of Lebanese civilians dead and coincides with a two-week-old Israeli military campaign in Gaza in response to the kidnapping of an Israeli soldier by Palestinian militants.