The U.S. Justice Department has rejected France's request to assist in investigating Elon Musk's X, calling the probe an inappropriate attempt to regulate an American company. In a two-page letter to French authorities, the department's Office of International Affairs said France's criminal investigation of the social-media platform's Paris office constitutes interference with free expression protected by the First Amendment.

The letter, dated Friday and reviewed by The Wall Street Journal, accused French officials of trying to entangle the United States in a politically charged proceeding. The Justice Department said France's requests for U.S. assistance amount to an effort to wrongfully regulate X's business activities through prosecution. This diplomatic clash follows a French raid on X's Paris office earlier this year.

The standoff highlights growing tensions between U.S. tech companies and European regulators over content moderation and platform governance. The Justice Department's intervention signals strong U.S. government support for protecting American tech firms from what it views as overreaching foreign investigations that could undermine constitutional protections.