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.

Chinese companies showcased A.I. gains in Shanghai this week. More chips will only help them improve faster, industry insiders say.

The US lifted its April ban on Nvidia’s H20 chip sales to China earlier this month. Following the reversal, both Nvidia and Advanced Micro Devices Inc. quickly resumed operations in the Chinese market, reclaiming their positions as leading AI chip suppliers to the country.