American stock markets shuddered on Monday, prompted by China's announcement that it has created a capable, cheap, artificial intelligence machine. It's the biggest cloud yet to darken the West's blue-sky enthusiasm over AI, calling into question the efficacy of America's export controls and the billions of dollars the United States is pouring into the technology's expensive cutting edge. China startup DeepSeek says its AI assistant uses less advanced chips than its rivals' models do, and it costs less to train. Unlike the West's billions, the Chinese model was developed for just 5.6 million, by one estimate. "Are we going to spend 500 billion to get to the frontier so that China can find a way to copy our homework for pennies on the dollar?"