When President Biden announced sharp restrictions in October on selling the most advanced computer chips to China, he sold it in part as a way of giving American industry a chance to restore its competitiveness. But at the Pentagon and the National Security Council, there was a second agenda: arms control. If the Chinese military cannot get the chips, the theory goes, it may slow its effort to develop weapons driven by artificial intelligence. That would give the White House, and the world, time to figure out some rules for the use of artificial intelligence in everything from sensors, missiles...