The decade-long Syrian conflict has evolved in various dimensions over its course and has seen participation of diverse internal and external actors throughout. The Syrian conflict theatre has been subject to change depending on the extent of engagement of regional and international actors. One such instance is the strengthening of Bashar al-Assad's position after the direct military involvement of Russia in Syria since September 2015. The role of external actors is significant in shaping the Syrian conflict; countries like US, Russia, Iran, Turkey, and Israel acted as per their interests and leverage in the region and contributed to the fate of conflict in their own way. All the players had different levels of stakes in or influence on the conflict and therefore can be perceived as core actors, peripheral actors, and the fence sitters.

External intervention escalates the conflict by emboldening the intrastate groups on the one hand; while on the other the hand, escalation of the conflict incites regional and international actors to intervene in the garb of protecting higher values like protection of human rights, maintenance of minimum order and promotion of democracy. Though more often than not the international actors intervene to protect their own geopolitical, economic or security interests. Any political or economic phenomenon that has originated in a particular political system and has an impact on the other can be defined as an intervention. Similarly, Beloff, Kelsen and Waltz identify use of coercion as an important factor while defining intervention. Numerous scholars have delved into studying the finer aspects of intervention including relevance of selective non-intervention as a kind of intervention. Power dynamics among the intervener and intervened has also been considered as a significant aspect of external intervention. Moreover, Rizvi defines intervention as an action, military or non-military, direct or indirect, taken by an actor in the international system (a state, group of states, international, regional or supranational organization) vis-à-vis the target state with the objective of changing its (the target state’s) policy outputs/extracting political concessions against its will, and altering or reinforcing its political authority pattern.