The fall of Aleppo in December emphasized the prominent role played by Lebanese Hezbollah in the Syrian war. Since 2013, Hezbollah fighters have operated across the border alongside the Syrian army and forces loyal to the regime of President Bashar Assad. Hezbollah’s importance is twofold: first, it has enabled the regime to wrestle back areas from rebel control, and second, it has significantly increased the effectiveness of pro-regime forces.