The Trump administration will make it harder for Samsung Electronics and SK Hynix to ship critical equipment to their chipmaking operations in China, dealing a potential blow to the companies’ production in the world’s largest semiconductor market.

Under a notice published Friday, the Commerce Department said it was revoking waivers for Samsung and SK Hynix to use U.S. technologies in their Chinese operations. The semiconductor companies had been operating in China under regulations that allow them to import chipmaking equipment without applying for a new license each time.

The Trump administration’s move would revise what’s known as the validated end user, or VEU, rules, handicapping the ability to make chips in the country and jeopardizing Beijing’s access to certain technologies.