TikTok went dark for American users in an unprecedented display of the U.S.-China divide over technology and national security.The app started halting service Saturday night for 170 million users in its most important market shortly before a law took effect requiring it to shed its Chinese ownership or close in the U.

As TikTok shut down on Saturday, a final message to US users suggested it was relying on President Trump to save the app.

President-elect Donald Trump says he “most likely” will give TikTok 90 more days to work out a deal that would allow the popular video-sharing platform to avoid a U.S. ban.