Russia and China are more natural allies with each other than either one would be with the US. From James George Jatras at strategic-culture.org:
Since 1991 and the formal end of the first Cold War between the United States and the Soviet Union, the world has experienced an American “unipolar moment” as the bipartisan US policy establishment sought to consolidate and perpetuate its hegemonic control over the entire plant. Doomed to fail even before it received its fullest articulation in 1996 by neoconservative ideologists William Kristol and Robert Kagan (misleadingly billed as “Toward a Neo-Reaganite Foreign Policy”), that misbegotten moment thankfully is coming to an end.
The main question today is whether the grinding to a halt of a quest so foolish and destructive can peacefully devolve into a tripolar entente among the US, Russia, and China – or whether the entrenched Washington establishment will, Sampson-like, crash everything down in a desperate but futile attempt to hang on to its power and privileges. We appear to be approaching the cusp at which that question will be resolved one way or the other. What the Trump Administration does next with respect to Iran will be a key, perhaps decisive, indicator.
However, of late there has emerged an alternative concept that may be seen as a middle way between America’s stubbornly hanging onto our diminishing hegemony versus working out a new Concert of Powers with the two countries the Trump Administration has dubbed rivals in a new “great power competition.” This concept suggests that the United States should play odd-man-out, teaming up with one of the other two powers against the third. Such a triangulation conceivably could perpetuate and enhance America’s global dominance (it is assumed the other nation would be the junior partner) while limiting the influence of the designated adversary.
To continue reading: There Will Be No American-Russian Alliance Against China