The US Supreme Court has upheld a divestment or ban law targeting TikTok, potentially leaving the video app facing the possibility of a blackout for its 170 million American users and putting its fate in the hands of President-elect Donald Trump.

The law obliges Tik TokChina’s parent company ByteDance has decided to sell the platform by January 19 – the day before Trump returns as US president – or face a nationwide ban.

“There is no doubt that TikTok, for more than 170 million Americans, provides a distinctive and broad outlet for expression, a means of engagement, and a resource for community,” the Supreme Court wrote in a unanimous opinion published Friday.

“But Congress determined that divestment was necessary to address well-supported national security concerns regarding TikTok’s data collection practices and relationship with a foreign adversary,” she added.

The decision by the country’s Supreme Court on Friday means the video app could “go dark” in one of its biggest markets. But the Biden administration said after the ruling that the outgoing president would not implement the ban during his remaining days in office.

The White House said: “Given the reality of the timing, this administration realizes that actions to implement the law must fall to the next administration, which takes office on Monday.”

“TikTok should remain available to Americans, but simply under U.S. ownership or other ownership that addresses the national security concerns Congress identified in developing this law,” she added.

Trump said in a mail on Truth Social after the ruling that “his decision on TikTok will be made in the not-too-distant future, but I should have time to review the situation,” adding that the court’s decision “was expected, and everyone should respect it.”

In a video posted on TikTok after the decision, the group’s CEO Xu Ziqiu did not offer any reassurances about whether the app would continue to operate in the United States on Sunday, but heaped praise on Trump.

“I want to thank President Trump for his commitment to working with us to find a solution that keeps TikTok available in the United States. “This is a strong position in favor of the First Amendment and against arbitrary censorship,” he added, adding that the president-elect “really understands” the program.

Unless a buyer for TikTok is found within days, it will be illegal for companies to offer services to distribute or host the video app, or face fines of $5,000 per user.

It is unclear whether technology groups such as Apple and Google will continue to make the app available in their app stores, or whether Oracle, which provides cloud and data services for TikTok in the US, will continue to do so as of Sunday. It is also unclear whether the company could also intentionally take offline to protect its partners. Apple, Google and Oracle did not immediately respond to requests for comment.

US Attorney General Merrick Garland said the decision “enables the Department of Justice to prevent the Chinese government from using TikTok as a weapon to undermine US national security.” “The next phase of this effort — implementing the law and ensuring compliance with it after it goes into effect on January 19 — will be a process that will continue over time,” Deputy U.S. Attorney Lisa Monaco added.

TikTok has said any spin-off would be technologically infeasible, while Beijing has previously indicated it would oppose any sale.

The court issued the ruling shortly after Trump announced on Friday that he had done so Discuss TikTok In a phone call with Chinese President Xi Jinping. This was the first contact between the two leaders in four years.

The Supreme Court ruling upholds one of the boldest legislative moves in Biden’s term just days before the Democratic president leaves the White House.

Mike Waltz, Trump’s new national security adviser, said Thursday that the legislation “allows for an extension as long as there is a viable agreement on the table.” This gives President Trump prime time to continue running TikTok.

Chinese officials have held preliminary discussions about whether billionaire Elon Musk — now a close ally of Trump — could broker a deal to sell the platform, the Financial Times reported. I reported this week.

Some potential buyers and partners have been circling Trump and lobbying him. Among them is Frank McCourt, the American media and sports tycoon, who has created a consortium of investors who will bid to buy TikTok through his non-profit entity, Project Liberty.

TikTok boss Chew launched a charm offensive to shore up support for Trump, including plans to attend the president-elect’s “victory rally” in Washington on Sunday and his inauguration on Monday, according to two people familiar with the matter.

The TikTok legislation, which passed with strong bipartisan support last year, was driven by concerns that Beijing could use the popular video platform for spying or to spread propaganda.

The Supreme Court said that although China “has not yet exploited its relationship with ByteDance Ltd to access TikTok user data in the United States,” there is “no basis for concluding that the government’s determination that China might do so is not ‘at least a reasonable decision.'” Inference[e] “Based on solid evidence.”

TikTok asked the Supreme Court to hear its case after the US Court of Appeals rejected its challenge to the law, as well as its subsequent request to stay the action pending further court action.

The social media app sought to overturn the law, arguing that it was unconstitutional and violated First Amendment protections for free speech.

Additional reporting by Amy Williams in Washington and Stephen Morris and Michael Acton in San Francisco