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.

Trump spoke to NBC News' Kristen Welker in an exclusive phone interview Saturday, discussing his plans on what to do about the popular social media app.

Users on the app were saying their goodbyes, some filming themselves frantically scrolling or sharing final secrets with their followers ahead of the possible ban.