The Trump administration Monday banned six Chinese companies that work on artificial intelligence from doing business with US firms, accusing the companies of helping to violate the human rights of Muslims in China's northwestern province of Xinjiang. Four of the companies, SenseTime, Megvii, iFLYTEK, and Yitu, make software for facial recognition and voice transcription that's reportedly been used in a campaign of repression and control in Xinjiang that has drawn international condemnation. The other companies, Hikvision and Dahua Technology, make surveillance equipment such as cameras that incorporates AI. Besides drawing attention to an important issue, the ban is also the latest effort by the US to curb China's progress in an increasingly important technology. "This is part of the broader tech cold war," says Rebecca Fannin, a technology consultant and author of Tech Titans of China, a book that charts China's recent progress in technology and innovation. The rise of China's tech industry has coincided, in recent years, with a revolution in AI.