President Donald Trump has announced he is banning the Chinese-owned video-sharing app TikTok in the US.
He told reporters he could sign an executive order as early as Saturday.
US security officials have expressed concern that the app, owned by Chinese firm ByteDance, could be used to collect the personal data of Americans.
TikTok has denied accusations that it is controlled by or shares data with the Chinese government.
The fast-growing app has up to 80 million active monthly users in America and the ban would be a major blow for ByteDance.
“As far as TikTok is concerned, we’re banning them from the United States,” Mr Trump told reporters aboard Air Force One.
It was not immediately clear what authority Mr Trump has to ban TikTok, how that ban would be enforced and what legal challenges it would face.
Microsoft has reportedly been in talks to buy the app from ByteDance, but Mr Trump appeared to cast doubt that such a deal would be allowed to go through. If the deal went ahead reports say it would involve ByteDance shedding TikTok’s US operations.
A TikTok spokesperson declined to comment on Mr Trump’s mooted ban, but told US media outlets the company was “confident in the long-term success of TikTok” in the US.
The move to ban TikTok comes at a time of heightened tensions between the Trump administration and the Chinese government over a number of issues, including trade disputes and Beijing’s handling of the coronavirus outbreak.