The United States has announced new restrictions on the export of semiconductors to China.

The U.S. Commerce Department said on Tuesday that it will prevent China from buying even slower versions of the U.S.’ advanced artificial intelligence chips that were previously allowed.

The department also announced that the export of U.S. semiconductors and chipmaking equipment to firms with a parent company in China, Macau and some 20 countries will be prohibited under U.S. arms embargoes in an effort to close loopholes in earlier export controls.

The decision was also made to expand licensing requirements for exports of advanced chips to 40 countries that present risks of diversion to China.

Washington also added 13 Chinese companies to its Bureau of Industry and Security Entity List, rendering them subject to rigorous license requirements and intense scrutiny.

Secretary of Commerce Gina Raimondo said that the updated rules will increase the effectiveness of U.S. export controls and further shut off pathways to evade the restrictions.