When the Chinese envoy Li Hui arrived in Saudi Arabia, to join international talks on a peace deal for Ukraine this week, it was a pointed contrast with Beijing’s decision to skip a similar forum in Copenhagen in June. At the summit, which excluded Russia, Ukraine’s leader Volodymyr Zelenskiy promoted his vision for ending the war to a large gathering of countries from the global south. His 10-point plan would mean the total, humiliating defeat of Vladimir Putin, Xi Jinping’s closest and most important major ally. China’s representative, a mid-level official with no policy-making powers, was not there to back...