China’s cyberspace regulator said Thursday that it had summoned representatives of U.S. tech giant Nvidia to explain alleged security vulnerability risks involving its highly sought-after H20 artificial intelligence chips.

Twenty national security experts and former government officials urge the Trump administration to reverse a decision to let Nvidia sell H20 AI chips in China.

China’s cyber regulator called upon Nvidia over tracking and serious security concerns with H20 graphic processing units. The move came after Washington lifted the ban on the AI chip