WASHINGTON, D.C.: U.S. President Donald Trump has moved to stop a small but sensitive semiconductor-related acquisition, ordering a U.S. photonics firm to unwind a deal involving aerospace and defense assets after determining it posed national security risks tied to China.

In an order released by the White House, Trump blocked HieFo Corp's US$3 million acquisition of assets from New Jersey-based aerospace and defense specialist Emcore.

The president said HieFo was "controlled by a citizen of the People's Republic of China" and that its 2024 acquisition of Emcore's businesses led him to believe the firm could "take action that threatens to impair the national security of the United States." The order did not identify the individual involved or provide further details on the specific concerns.

"The Transaction is hereby prohibited," Trump said, directing HieFo to "divest all interests and rights in the Emcore Assets, wherever located," within 180 days.

The decision followed a review by the Committee on Foreign Investment in the United States, which identified a national security risk during its investigation of the transaction, the Treasury Department said after the order was issued. The statement did not specify what that risk entailed.

HieFo and Emcore could not be reached for comment immediately and had not posted a response on their websites as of late Friday.

Emcore, which was publicly traded at the time of the transaction and later taken private, has said HieFo purchased its chips business and indium-phosphide wafer-fabrication operations for $2.92 million.

At the time of the deal, HieFo said it was co-founded by Genzao Zhang, a former Emcore vice president of engineering, and Harry Moore, whose LinkedIn profile describes him as a former senior sales director at Emcore.