The last time Syrian President Bashar Assad was in serious trouble was 10 years ago, at the height of the country’s civil war, when his forces lost control over parts of the largest city, Aleppo, and his opponents were closing in on the capital, Damascus. Back then, he was rescued by his chief international backer, Russia, and longtime regional ally Iran, which along with Lebanon’s powerful Hezbollah militia helped Assad's forces retake Aleppo, tipping the war firmly in his favor.