WASHINGTON — TikTok was unavailable to many of its 170 million users in the United States hours before a ban on the popular social media platform was expected to officially take effect.

On Saturday night, TikTok addressed some users who had opened the app, saying: "Sorry, TikTok is currently unavailable."

"The United States has enacted laws banning TikTok," the message continued. “Unfortunately, this means you can’t use TikTok right now. We are lucky that President Trump has said he will work with us on solutions to restore TikTok once he takes office. Stay tuned!”

The message then prompts the user to close the application or learn more.

The app also appears to have been removed from U.S. app stores on Saturday night and is unavailable for download.

CapCut, a popular editing app among TikTok users, showed similar information and was also unavailable to many U.S. users Saturday night.

TikTok's shutdown comes after days of tense uncertainty for the app leading up to Sunday when a ban on TikTok was expected to take effect in the United States.

U.S. President Joe Biden signed a law last year forcing TikTok's Chinese parent company ByteDance to sell TikTok or face a ban on the app. The Supreme Court upheld the law on Friday, paving the way for the app to be shut down in the United States.

But the Biden administration issued a statement on Friday saying it would leave enforcement of the law to the Trump administration, comments that raised uncertainty about whether the app would be available Sunday.

Lawmakers from both parties have denounced TikTok as a national security threat because it is owned by a Chinese company. TikTok critics argue the Chinese government could use the app to access Americans' data or influence the type of content Americans watch.

But the company pushed back against lawmakers' concerns, instead describing the looming ban as a free speech and censorship issue. TikTok CEO Shou Chew says the app is safe and secure

The future of the app is far from certain. Earlier on Saturday, President-elect Donald Trump told NBC News' Kristen Welker that he would "probably" extend the app's Sunday deadline by 90 days to allow ByteDance to sell the app Procedures to ban TikTok in US

"A 90-day extension is the most likely thing to get done because it's appropriate," Trump said.

Trump's stance on TikTok has shifted. In 2020, he said he wanted to ban the app. Years later, Trump changed his stance and created his own TikTok account during the 2024 presidential campaign.