I've now heard this story reported on a few different networks and it's very strange the way Fox is reporting this as though the US and Russia are about to start shooting at each other (which is not the case) .
The Russians are essentially just bombing whatever, just to make Assad look stronger.
Russia is bombing ISIS -and- the "moderate" terrorists.
Anyone that thought Russia would just attack ISIS while American backed Al Qaeda fighters would be free to conquer the rest of Syria is utterly and hopelessly naïve.