The agreements relate to three different conflict contexts. Israel-Syria and Syria-Lebanon. The Syrian-Israeli conflict was a key factor for the Syrian intervention during the Lebanese Civil War, with Syrian-backed Palestinian Liberation Army units intervened in 1976 against the Palestinian/Leftist militias. Following a massacre at Tel al-Zaatar that year, Syria was forced to accept a ceasefire at a meeting of the Arab League. However, the Arab League also mandated an Arab Deterrence Force, consisting of mostly Syrian soldiers with token contributions from other Arab League states, thus further legitimizing the Syrian presence in Lebanon. During a second bout of fighting that began in 1989, caused by the formation of rival Lebanese regimes in East and West Beirut, the Syrian-backed regime won and in 1991 the ‘Treaty of Brotherhood, Cooperation and Coordination’ was signed to legalize the Syrian occupation as a means to ensure the security of Syria. Syrian forces were forced to withdraw in 2005 following possible involvement in the assassination of Lebanon’s President Hariri.
Syria-internal. In 2011, domestic upheaval following a wave of protests across the Arab World soon led to violent repression of protestors by Syrian government troops. The violence progressed steadily and by July 2011 the Free Syrian Army (FSA) was formed consisting of defected military units and new recruits. The FSA and rebel umbrella group known as the Syrian National Council represented the first attempt at coordinating rebel factions in late 2011. However, a steady influx of foreign fighters and increased sectarianism radicalised opposition groups, which relied on foreign funding. The nature of the conflict changed drastically in late 2013 as infighting among the opposition groups increased. One of the more significant developments was the split between the al-Qaeda outfits the Islamic State in Iraq and the Levant (ISIL, ISIS), and Jabhat al-Nusra in early 2014 in addition to the intensified targeting of other rebel factions by ISIS fighters in particular, including the Kurdish Peshmerga, the FSA and other jihadist outfits. Since the summer of 2014, the conflict was further internationalized when ISIS announced the formation of an Islamic state eroding the state line between Iraq and Syria and also in mid-2015 when Russian forces intervened on behalf of the Bashar al-Assad government in Damascus.