AP Photo

Since the beginning of the twenty-first century, China and Russia have been constants in the world. They have been autocratic, resistant to the spread of freedom, occasionally belligerent toward their neighbors, and increasingly prosperous. They have consistently joined together in order to block Western initiatives in the UN Security Council and to defend dictatorships like Iran, North Korea, and Syria.

The two countries have created the illusion of durability. Vladimir Putin has just begun a six-year presidential term, with an option for another. Hu Jintao and Wen Jiabao are planning to hand over power in October to a new tandem, Xi Jinping and Li Keqiang, who are expected to serve for ten years. Yet the evidence is growing that the apparent stability in Russia...