In Silicon Valley, the nightmare keeping computer scientists up is an artificial intelligence so advanced that humans cannot stop it from launching a global drone war or setting off a nuclear bomb.

In Beijing, the response could be simple: pull the plug, impose an internet blackout and haul in those responsible for the rogue A.I. During the pandemic, the government showed its ability to contain major crises by locking down entire cities and tracking hundreds of millions of residents. “They can immediately cut off the grid of the entire city. They can go to different people to take away their phones. They have an intense amount of power in the physical world,” said Afra Wang, a Silicon Valley-based tech writer focusing on A.I. and technology in China.