The Supreme Court signaled in oral arguments Friday that it may uphold the federal ban on TikTok, potentially leaving it up to President-elect Donald Trump to try and keep the app legal once he takes office — but the president-elect has limited options if the law is upheld, and any attempts to stop it could be challenged in court.

Congress says the popular video app poses a looming threat to the nation’s security because of its Chinese owner. What the justices decide could determine if the app is shut down.

The court is hearing oral arguments on TikTok’s bid to block a law that would lead to its ban in the U.S. starting Jan. 19 if it isn’t sold by its Chinese owner.