As rebel-held sections of Aleppo crumbled under Russian bombing this month, the Obama administration was secretly weighing plans to rush more firepower to CIA-backed units in Syria. The proposal, which involved weapons that might help those forces defend themselves against Russian aircraft and artillery, made its way onto the agenda of a recent meeting President Obama held with his national security team. Obama, officials said, now seems inclined to leave the fate of the CIA program up to the next occupant of the White House. If so, Obama’s successor will inherit an array of unattractive options. But inaction has its own risks — increasing the likelihood that Aleppo will fall, that tens of thousands of CIA-backed fighters will search for more-reliable allies, and that the United States will lose leverage over regional partners that until now have refrained from delivering more-dangerous arms to Assad’s opponents.