The Friday decision comes after Congress passed a law last year that was signed by President Joe Biden, giving TikTok parent ByteDance a Jan. 19 deadline to divest the company or face a ban in the country.  

The justices ruled that the law furthers the interest of national security and that banning TikTok doesn’t burden “substantially more speech than necessary” to accomplish this.

“The Act’s prohibitions and divestiture requirement are designed to prevent China—a designated foreign adversary—from leveraging its control over ByteDance Ltd. to capture the personal data of U. S. TikTok users,” the ruling read. “This objective qualifies as an important Government interest under intermediate scrutiny.”

Yet while Biden signed the act that established the impending TikTok ban, he will not implement the law, the Associated Press reported, citing an anonymous U.S. official. Instead, he will leave the decision on whether to enforce the ban to Trump, who is set to be inaugurated as president on Monday, a day after the ban is to take place.

The incoming president previously supported a TikTok ban and tried to pass a law banning the app during his first term. Yet he changed his stance during the campaign.

On his social media website Truth Social, Trump said a decision on TikTok would come soon. When reached for comment, a spokesperson for the Trump transition team directed Fortune to the president-elect’s post.

“The Supreme Court decision was expected, and everyone must respect it. My decision on TikTok will be made in the not too distant future, but I must have time to review the situation. Stay tuned,” Trump wrote in the Friday post.

Trump’s incoming national security adviser, Congressman Mike Waltz, meanwhile, said this week that the president-elect would not let the ban take effect.

“We will put measures in place to keep TikTok from going dark,” Waltz told Fox News.

He added that the law “allows for an extension as long as a viable deal is on the table.” The 90-day extension triggered by a viable deal could offer TikTok a reprieve, but it’s unclear whether it would apply if the deadline passes.

It’s unclear as well whether TikTok is seriously considering any deal. A group of investors including Frank McCourt, the executive chairman of McCourt Global, and Shark Tank star Kevin O’Leary made a formal offer last week to buy TikTok. Chinese officials have also reportedly considered selling to Elon Musk, Bloomberg reported, although TikTok called the idea of selling to Musk “pure fiction.” 

The fact that the Chinese government would also need to approve any sale of TikTok further complicates finding a deal to sell off TikTok’s U.S. assets.

TikTok did not immediately respond to Fortune’s request for comment. 

Experts have said once the ban takes effect Sunday, the app will no longer be available on third-party app stores for download. But the app won’t disappear from smartphones that have already downloaded it. Using a VPN (virtual private network) could also let U.S. users get around the ban.

Still, ByteDance has threatened to shut down the app down, and third-party providers may not want to risk supporting TikTok when the ban takes effect, despite Biden signaling he won’t enforce it.

And without updates or maintenance, TikTok will likely become useless or dangerous for those that continue to use the app they have on their phone following the ban.

“Potentially, vulnerabilities will become known in the app, and hackers will take advantage of those vulnerabilities to compromise your account or your device,” Eva Galperin, director of cybersecurity at the Electronic Frontier Foundation, told CNN.