Images shared on social media have illustrated the anger that Syrian rebels fighting President Bashar al-Assad feel toward his ally Vladimir Putin. The Russian leader has been indispensable in propping up Assad's regime during the brutal Syrian civil war that started in 2011 but has been essentially frozen over the last four years.

Syria carried out airstrikes targeting the rebel forces that seized the country's second largest city of Aleppo in a surprise advance last week that caught the government off guard.