A/HRC/28/69 122. The increasing engagement of these players has led to a spillover of violence into their countries of origin. The military intervention of Hizbullah and Iraqi Shia militia on the side of the Government and the involvement of thousands of extremist militants in support of the rebels have heightened the pre-existing risks of instability in neighbouring States. The continuous armed confrontations in northern Lebanon and the rise of ISIS and its subsequent offensive in Iraq are indicators of the increased regionalization of the crisis. 123. Owing to their background and the narrative they use to justify their presence and operations in the Syrian Arab Republic, non-State actors have accentuated violence along sectarian lines, further aggravating religious and ethnic divisions. 124. Non-State players have also fuelled the radicalization of the belligerents, in particular of armed groups. In supporting the anti-government armed groups, charity organizations and private donors interested in the spread of extreme ideologies have privileged groups willing to endorse their beliefs. 3. Flow of foreign fighters resulting in the rise of extremism and terrorism 125. Predominantly driven by hardline religious ideology, foreign fighters who joined non-State armed groups initially gained prominence among their counterparts owing to their efficient involvement in both operational and governance activities. The respect they secured or the fear they enforced among local communities in areas held by armed groups has enabled them to influence the landscape in the direction of extremism. 126. The engagement of foreign fighters has benefited the extremist groups, such as ISIS and Jabhat Al-Nusra. These groups, designated as terrorist groups under Security Council resolution 2170 (2014), have used their fighting skills and, more importantly, their ability to use their ideology to effectively mobilize and recruit fighters. This has accentuated the supremacy that these groups have gained over the mainstream armed groups throughout the war, particularly in 2014. 127. These fighters have driven the radicalization process in areas held by armed groups. Besides their military engagement, they have also played a prominent role in religious, educational and judiciary “systems” established in these areas. Control of these fundamental aspects of civilian life will further radicalize communities under their authority. C. Responsibility of the United Nations system 128. After more than two years of inaction on the crisis in the Syrian Arab Republic, the Security Council adopted resolution 2118 in September 2013, in which it required the verification and destruction of chemical weapons stockpiles, calling for the convening of the Geneva II peace talks and endorsing the establishment of a transitional governing body with full executive powers. 129. As the crisis worsened, the Security Council adopted resolution 2139 in February 2014. In the resolution, the Council requested that all parties, in particular the Government, allow humanitarian access across conflict lines, in besieged areas and across borders. The scope of resolution 2139 (2014) was broadened with the adoption of resolution 2165 (2014), in which the Council authorized cross-border and cross-line access for the United Nations and its partners to deliver humanitarian aid without State consent. In its resolution 2191, adopted in December 2014, the Council renewed its authorization to use routes across conflict lines as well as specified border crossings. It also renewed the monitoring mechanism created by that resolution. 19