For decades, China and Russia have had a tense relationship. This was a function of their very long border with one another, particularly during the Soviet era, and the US efforts to cultivate an alliance with China.
But things change. The US has been treating both China and Russia as strategic rivals in recent years, and that hostility is driving both nations to rethink their relationships across the world, including with one another. This has brought the two rivals close together.
This is demonstrated by an upcoming Russian military drill, which has tended to be a source of tension with China. This year, China has been invited to participate, something which once would’ve been unthinkable.
Now, they’re not competitors in Asia, or rivals vying for superpower status. Instead, they see the huge US military and the increasingly surly US policy toward both of them as aligning their interests, and bringing them together to face a common enemy.
US officials see growing closeness between Russia and China as intended as a “message” for them. In reality, it’s the inevitable product of US policy, which has treated both Russia and China as enemies to be dominated.