Supply Lines is a daily newsletter that tracks Covid-19's impact on trade. Sign up here, and subscribe to our Covid-19 podcast for the latest news and analysis on the pandemic. China imposed new restrictions on the export of artificial intelligence technologies, signaling it may step in to block Beijing-based ByteDance Ltd. from selling the U.S. operations of its TikTok short-video app. AI interface technologies such as speech and text recognition, and those that analyze data to make personalized content recommendations, were added to a revised list of export-control products published on the Ministry of Commerce's website late Friday. Government permits will be required for overseas transfers to "safeguard national economic security," it said.