US President Donald Trump has signed an executive order to ban transactions with TikTok’s parent company ByteDance.
The executive order says the US “must take aggressive action against the owners of TikTok to protect our national security”.
Under the order, beginning in 45 days, any US transaction with ByteDance will be prohibited.
TikTok denies accusations it is controlled by or shares data with the Chinese government.
On Thursday night, he also took similar action to ban WeChat, an app owned by China-based tech giant Tencent.
In the TikTok executive order, he says he has found “additional steps must be taken to deal with the national emergency with respect to the information and communications technology and services supply chain”.
“Specifically,” he adds, “the spread in the United States of mobile applications developed and owned by companies in the People’s Republic of China (China) continues to threaten the national security, foreign policy, and economy of the United States.
“At this time, action must be taken to address the threat posed by one mobile application in particular, TikTok.”
Mr Trump said TikTok’s data collection could allow China to track US government employees and gather personal information for blackmail, or to carry out corporate espionage.
He noted that reports indicate TikTok censors content deemed politically sensitive, such as protests in Hong Kong and Beijing’s treatment of the Uighurs, a Muslim minority.
The US president said the Department of Homeland Security, the Transportation Security Administration (which oversees US airport screening) and the US Armed Forces have already banned TikTok on government phones.