In China, a forbidden question looms: Who leads after Xi?

Foreign observers looking for clues at this week's Communist Party Central Committee meeting are likely to be disappointed.

- Chris Buckley

Behind closed doors in Beijing this week, China's top officials are meeting to refine a plan to secure its strength in a turbulent world.

But two great questions hang over the nation's future, even if no one at the meeting dares raise it: How long will President Xi Jinping rule, and who will replace him when he is gone?

Mr Xi has led China for 13 years, amassing dominance to a degree unseen since Mao Zedong. He has shown no sign of wanting to step down. Yet his longevity at the top could, if mismanaged, sow the seeds of political turbulence: He has neither an heir apparent nor a clear timetable for designating one.

With each year that he stays in office, uncertainty deepens about who would step in if, say, his health failed, and whether the new leader would stick to or soften Mr Xi's hard-line course.

Mr Xi faces a dilemma familiar to that of long-serving autocrats. Naming a successor risks creating a rival centre of power and weakening his grip, but failing to settle on a leader-in-waiting could jeopardise his legacy and sow rifts in China's political elite. And at 72, Mr Xi will likely have to search for a potential heir among much younger officials, who must still prove themselves and win his trust.

If Mr Xi eventually chooses a successor, loyalty to him and his agenda will almost surely be a paramount requirement. He has said that the Soviet Union made a fatal mistake by picking reformer Mikhail Gorbachev, who oversaw its dissolution.

On Oct 17, Mr Xi made his intolerance for any disloyalty clear when the military announced that it had expelled nine senior officers, who face prosecution on charges of corruption and abuse of power.