In the winter of 2012, when the civil war in Syria had already consumed tens of thousands of lives, Vladimir V. Putin , the Russian president, sounded dismissive of Syria’s beleaguered leader, Bashar al-Assad , and unconcerned about his future. Mr. Assad, he said, acidly, had spent more time courting leaders in European capitals than he ever had in Moscow. “We are not that preoccupied with the fate of Assad’s regime,” Mr. Putin said then. Three years later, the two presidents have bound themselves together in an alliance that reflects not only the urgent priority of salvaging the crumbling central government in Syria, but also each man’s eroded standing on the international stage. Mr. Putin’s military has forcefully intervened to shore […]