Sino-Russian relations have been shaping the agenda of Eurasian and global politics for at least one century. Over most of the time since World War II, the two countries have had similar political regimes. Having abortively flirted with liberal democracy during the initial post-Soviet years, Russia settled for missionary authoritarianism by the second decade of Vladimir Putin’s tenure as Russian president. China followed a similar trajectory under Chairman Xi Jinping, fanning nationalist sentiment and bracing for an open conflict with the United States and its allies over Taiwan, control of the seas around China, and the terms of economic engagement between China and advanced Western economies.