The letter said the licensing regime will be in place “pending the U.S. government’s review of SMIC and its subsidiaries.”

The Pentagon earlier this month said the Trump administration was considering adding SMIC to the Entity List, a trade blacklist that would block U.S. technology sales unless companies receive a license.

The Commerce Department “has determined that exports to SMIC or its subsidiaries, including those listed above, may pose an unacceptable risk of diversion to a military end use in the People’s Republic of China pending the U.S. government’s review of SMIC and its subsidiaries,” said the letter, which was reported earlier by the Financial Times and the Wall Street Journal.

SMIC and other chip manufacturers depend on U.S. software and chip-making machinery to produce semiconductors.

The Commerce Department declined to comment on the letter but said it is “constantly monitoring and assessing any potential threats to U.S. national security