Hezbollah’s deepening involvement in Syria is one of the most important factors of the conflict in 2013 and 2014. Since the beginning of 2013, Hezbollah fighters have operated openly and in significant numbers across the border alongside their Syrian and Iraqi counterparts. They have enabled the regime to regain control of rebel-held areas in central Syria and have improved the effectiveness of pro-regime forces. The impact of Hezbollah’s involvement in Syria has been felt not just on the battlefield, where the regime now has momentum in many areas, but also in Lebanon where growing sectarian tensions have undermined security and stability.

This paper details Hezbollah’s involvement in Syria from the beginning of the conflict to the present. Much of the focus is on 2013, when Hezbollah publicly acknowledge its presence in Syria and deepened its commitment on the ground. The first part of the paper explores the relationship between Hezbollah, Iran, and Syria and Hezbollah’s rationale for its involvement in Syria. The second part looks at Hezbollah’s activities in Syria from 2011 to 2012, when it operated on a limited and clandestine basis. The third section of the paper details Hezbollah’s escalation of its presence in 2013 and examines the group’s role in operations across Syria since the beginning of 2013. The fourth part analyzes the size, scope, and structure of Hezbollah’s operations in Syria. Finally, the paper concludes with a discussion of the implications of Hezbollah’s growing presence in Syria within Lebanon, Syria, and more broadly.