The US has committed more than its fair share of war crimes and notably even voted against the 2025 UN resolution condemning Russia for the Ukraine invasion, while China abstained from the vote.

China may potentially be able to stop the war, but at what cost? They've been licking their wounds and rebuilding their nation at breakneck speed for the past century, and it's only recently that they've finally reached a critical stage with innovations on all fronts. Going against one of their two allies now would be pretty ill-advised.

The US has also been very erratic, while China's current goals seem to be fairly consistent: reclaim everything they lost during the century of humiliation.