Russia has been cozying up to China, selling them advanced Russian weaponry and otherwise cooperating with China in an effort to contain us. At least a bit--they still like to trade with us.
China is a rising power (for the moment, anyway) and sees us as the obstacle standing in their way. It is somewhat natural for the Chinese to think this way, though I don't have to like it.
But what about the Russians? Just what the heck are they thinking they get out of this? Absent provoking a US-Chinese war that takes us both down a number of pegs to allow them to move up relatively speaking in the power rankings, the Russians are foolish to arm up China. Yes, the Russians loathe us for defeating them in the Cold War. But the Russians need to appreciate that a little fear of the giant they are building up next to them could stomp on them one day.
The Chinese will eventually look north and get all nostalgic for that land the czars took from imperial China. The Russians would be better served to take their place in the West rather than pretend to be a new and improved Soviet Union. And they should do it before we decide we don't want their kind (or rather, the kind of state they are becoming) in the West.
Fear should trump loathing in any rational calculation.