After 13 years of civil war and a long period of stalemate, Syrian rebels swept into Damascus, bringing an end to the Assad regime that has ruled Syria for 53 years. Bashar al-Assad, who had been president since 2000, fled to Moscow. Social media depicted scenes of jubilation in the capital. The rebels were led by Hayat Tahrir al-Sham, an Islamist group. One of its leaders, Muhammad al-Bashir, is to head a caretaker government until March. The fall of the Assad regime is a huge blow to Iran, which is also contending with the dismantling of Hizbullah, its proxy in Lebanon, by Israel. And also to Russia. Its main military force in the Mediterranean is based at Syrian ports.