When President Trump and President Xi Jinping of China meet in Beijing this week, they are expected to discuss, for the first time, how to manage the risks of artificial intelligence. But in many ways, the two countries seem farther apart than ever on that question.The United States and China are racing to develop AI-powered weapons that could wreak immense damage without human involvement. Powerful new AI models could enable cyberattacks that might cripple the world’s banks and power grids. Experts have also raised the alarm about how AI could be misused by terrorists or even become sentient and wipe...