Lebanon is the most politically complex and religiously divided country in the Middle East, which is what makes it such a potentially explosive factor in an unstable region.
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UNSCR 1701 which passed in August 2006, called for the disarmament of Hizballah.
Israel's withdrawal from southern Lebanon in May 2000 encouraged some Lebanese groups to demand that Syria withdraw its forces as well. UNSCR 1559called for Syria to withdraw from Lebanon and end its interference in Lebanese affairs.
On November 13, 2006, Hezbollah-Amal-backed ministers resigned from Siniora's cabinet to protest the establishment of the international tribunal investigating the assassination of PM Rafiq Hariri in 2005, which the Siniora government, as well as the United States, have accused the Syrian intelligence service of involvement in, a charge denied by Syria.With the resignation of these cabinet ministers, and under Lebanon's constitution the Siniora government no longer legitimately holds power, as the constitution requires all Lebanese ethno-religious groups to be represented in the cabinet. They demand an increase in opposition representation in the cabinet, sufficient to hold veto power over decision making, as their requirement for returning. The government sees this as a Syrian-orchestrated move to block the establishment of the Hariri tribunal.
From The World Factbook:
Following the capture of Syria from the Ottoman Empire by Anglo-French
forces in 1918, France received a mandate over this territory and separated out
a region of Lebanon in 1920. France granted this area independence in 1943. A
lengthy civil war (1975-1990) devastated the country, but Lebanon has since made
progress toward rebuilding its political institutions. Under the Ta'if Accord -
the blueprint for national reconciliation - the Lebanese established a more
equitable political system, particularly by giving Muslims a greater voice in
the political process while institutionalizing sectarian divisions in the
government. Since the end of the war, Lebanon has conducted several successful
elections, most militias have been disbanded, and the Lebanese Armed Forces
(LAF) have extended authority over about two-thirds of the country. Hizballah, a
radical Shi'a organization listed by the US State Department as a Foreign
Terrorist Organization, retains its weapons. During Lebanon's civil war, the
Arab League legitimized in the Ta'if Accord Syria's troop deployment, numbering
about 16,000 based mainly east of Beirut and in the Bekaa Valley. Damascus
justified its continued military presence in Lebanon by citing Beirut's requests
and the failure of the Lebanese Government to implement all of the
constitutional reforms in the Ta'if Accord. Israel's withdrawal from southern
Lebanon in May 2000, however, encouraged some Lebanese groups to demand that
Syria withdraw its forces as well. The passage of UNSCR 1559 in early October
2004 - a resolution calling for Syria to withdraw from Lebanon and end its
interference in Lebanese affairs - further emboldened Lebanese groups opposed to
Syria's presence in Lebanon. The assassination of former Prime Minister Rafiq
HARIRI and 20 others in February 2005 led to massive demonstrations in Beirut
against the Syrian presence ("the Cedar Revolution"). Syria finally withdrew the
remainder of its military forces from Lebanon in April 2005. In May-June 2005,
Lebanon held its first legislative elections since the end of the civil war free
of foreign interference, handing a majority to the bloc led by Saad HARIRI, the
slain prime minister's son. Hizballah kidnapped two Israeli soldiers in July
2006 leading to a 34-day conflict with Israel. UNSCR 1701, which passed in
August 2006, called for the disarmament of Hizballah.