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.

If the Supreme Court decides not to intervene, TikTok will be unavailable everywhere in the U.S., including in Wisconsin, starting Jan. 19.