Syria's modern presence in Lebanon, which ended in 2005 under pressure from the international community, began in 1976 when Lebanese President Suleiman Franjieh called for support from Syrian troops in response to fighting that had escalated into the country's second civil war in less than 20 years. The war, between the Maronite Christians in power and Sunni and Shiite Muslims and Druze, over who should control the government, would go on for 15 years and leave an estimated 100,000 people dead.

In October 1976, just months after Syria entered Lebanon, Arab summit meetings convened in Riyadh, Saudi Arabia, to devise a plan to end the war. The group formed the Arab Deterrent Force, or ADF, a force of mainly Syrian soldiers charged with ending the fighting and instituting peace.

Soon after the formation of the ADF, however, relations between Syria and Franjieh's Christian militias soured and Lebanese troops began warring with Syrian troops.

As Syria struggled to keep the peace in Beirut, a second conflict was brewing in the southern region of the country. In 1978, in response to an attack on Israeli soil by militants believed to have come from Palestinian refugee camps in Lebanon, Israel invaded southern Lebanon beginning a decade-long conflict that eventually would draw in five countries.

Israel soon joined Lebanese Christians in ousting Syrian troops -- then aligned with Lebanese Muslim militias -- from Beirut. It was not until 1985, when Israel began to withdraw from Lebanon, that Syria was able to regain control of the country.

The Taif Accord and U.N. Resolution 1559
As a means to end the war in Lebanon, the country's parliament met in the Saudi resort town of Taif in 1989 and signed the Taif accord, an agreement that ended fighting and formed a power-sharing government jointly controlled by Christians and Muslims. The accord also served as Lebanon's new constitution.

As part of the accord, the Lebanese parliament, with support from the Arab League, called for a special relationship between Syria and Lebanon -- one of "brotherhood" and coordination, according to a State Department profile on Syria -- with Syria assisting the government in controlling of the country over the next two years.

While the Taif agreement did outline a framework between the two countries for the withdrawal of Syria's 40,000 troops by 1992, Syria and Lebanon -- the countries charged with enacting such a pullout -- failed to do so.

The measures of the Taif accord would become a source of contention between pro-Syrian demonstrators and supporters of the French and U.S.-sponsored U.N. Security Council Resolution 1559 signed in September 2004, which called for the immediate withdrawal of Syrian troops.

According to Syrian backers in Lebanon, the accord and its mandate that Lebanon and Syria jointly make the decision about a timetable for withdrawal, took precedence over the U.N. resolution.

"All Lebanese factions and political parties agree on the Taif agreement," said Middle East scholar Murhaf Jouejati. "Those political parties who are loyalists to Syria they didn't want a Syrian withdrawal under pressure from the United States, they are thankful to Syria for having stabilized Lebanon and they wanted the withdrawal to be one of honor not of pressure."

Syria's legacy in Lebanon
In the years following the Taif agreement, Syria not only maintained between 14,000 and 40,000 troops in Lebanon, but also imposed a keen grip on the country's politics and economy.

An estimated 1 million Syrians lived and worked in Lebanon, according to the U.S. Department of Defense, and critics say the pro-Syrian Lebanese government continued to answer to Damascus.

Along with these more overt Syrian influences, American officials also criticized the presence of the Syrian intelligence agency, an arm of the Syrian government known as the "mukhabarat," through which Syria maintained control over much of the daily life in Beirut.

"It's the worst intelligence apparatus in history, everyone's terrified of them," a taxi driver who would give his name only as Khaled told the Reuters news service in March 2005.

Such influence is what led to the resignation in October 2004 of former Lebanese Prime Minister Rafik Hariri, a popular businessman and politician credited with rebuilding much of Beirut after the war. Hariri, along with members of Lebanon's opposition parties, objected to Syria's hold on the government and called for the withdrawal of troops leading up to the general election in May 2005.

Prior to Hariri's resignation, in an example of Syria's dominance, Syrian leaders lobbied the Lebanese parliament to pass a controversial amendment to the constitution extending the term of pro-Syrian President Emile Lahoud.

On Feb. 14, 2005, Hariri was assassinated in a car bomb explosion that killed he and 15 others. Opposition leaders and Hariri's family accused the Lebanese and Syrian governments of having a hand in the killing and demanded an international investigation into his death. The United Nations launched an investigation soon after. A final report is pending.

Hariri's death, and the protests that followed, proved to be the most difficult test of Syria's Lebanon policy since the withdrawal of Israeli troops. Under the glare of the international spotlight, Syrian leaders agreed to expedite the Taif pact and withdrew their troops from Lebanon after nearly 30 years.

-- Compiled by Kristina Nwazota for the Online NewsHour