Hezbollah was dealt a major blow during 14 months of war with Israel. The toppling of Assad, who had strong ties to Iran, has now crippled its ability to bounce back by cutting off a vital weapons-smuggling route through Syria.

The ascendance of Sunni Islamist rebels in Syria should be viewed with great caution by Western powers, but the Assad regime’s collapse disables a critical node in Iran’s regional proxy network, a counterterrorism expert explains.