Why would Russia and China want to weaken the dollar? Did you completely miss that Russia and China both criticized our OWN efforts to weaken the dollar via quantitative easing less than a month ago?
Did you miss the fact that the yuan is pegged to the dollar, and therefore it is IMPOSSIBLE for them to weaken the dollar by switching from the dollar to their own currency?
Why are Russia and China under any moral obligation to use the dollar for their mutual trading, any more than the US and Canada use the euro when trading with one another?
Does your "Cold War" analogy have any substance at all, beyond the fact that you saw the words Russia and China and detected some vague conspiracy against the United States? Do you even know the history of the Cold War? Russia and China were hardly allies for the vast majority of it.