The United States has moved to restrict South Korean chipmakers Samsung Electronics and SK Hynix from producing advanced semiconductors in China, revoking special authorizations that had allowed them to import American equipment, according to the Federal Register.

The Commerce Department had granted the companies exemptions from sweeping 2022 export controls on U.S. chipmaking tools bound for China. But those exemptions will now end, stripping Samsung and Hynix of their “Validated End User” (VEU) status, which had let U.S. suppliers ship equipment to them more quickly and with fewer hurdles.

The decision comes amid renewed tensions in U.S.-China trade relations. Washington and Beijing are currently under a tariff truce—30% U.S. duties on Chinese imports and 10% Chinese tariffs on U.S. goods—set to last until November. Officials had signaled earlier this year that revoking the authorizations was a possibility if trade talks faltered.

Meanwhile, thousands of U.S. companies face delays on export license applications to China, leaving billions of dollars’ worth of semiconductor equipment and other goods stuck in limbo.

The White House declined immediate comment.