President Trump signed an executive order Thursday that will prohibit transactions with social media app TikTok’s parent company, ByteDance, and is threatening to impose sanctions on violators who fail to comply. 

The order would ban “any transaction by any person, or with respect to any property, subject to the jurisdiction of the United States.” It is not clear if the ban will affect the millions of U.S. users who are avid fans of the app. 

The ban is set to take effect in 45 days, which is the period of time that Mr. Trump agreed to give ByteDance to negotiate a deal to sell its U.S. operations, Reuters reported. Microsoft said it is in discussions with Beijing-based ByteDance about a possible acquisition, and has said it hopes to clinch a deal by September 15. Microsoft CEO Satya Nadella spoke last weekend with Mr. Trump.

The order states that the action is being taken to address the threat to the nation’s “national security, foreign policy and economy” posed by the spread in the U.S. of “mobile applications developed and owned by companies in the People’s Republic of China.”  

The app “automatically captures vast swaths of information from its users,” like internet activity, location data, and browsing history, and it potentially gives China access to Americans’ personal information. The order contemplates the possibility that the Chinese could compile “dossiers of personal information for blackmail” and conduct “corporate espionage” against federal employees and contractors, the order said.

Days ago, President Trump threatened to ban TikTok from the U.S. through executive action. The social media app, popular with young users, has prompted concerns about the safety of Americans’ personal data. The U.S. Army has banned the use of TikTok on official devices, and India has banned the app entirely. But the company claims it’s committed to protecting its users’ privacy and has said in a statement that its user data is “stored in the U.S., with strict controls on employee access.”

Mr. Trump also signed a similar order Thursday targeting another social media and messaging app, WeChat, which is owned by Tencent Holdings, another Chinese company. The president said in his order, “Like TikTok, WeChat automatically captures vast swaths of information from its users,” and charged that the app also captures personal information belonging to Chinese nationals visiting the U.S., allowing the Chinese government to track them.

Gabrielle Ake contributed reporting.