President-elect Donald Trump backed TikTok in a Truth Social post Friday as his incoming administration has asked the Supreme Court to stop the federal ban on TikTok from taking effect until after Inauguration Day—but the president-elect has limited options if the law is upheld, and any attempts to stop it could be challenged in court.

“​​President Trump opposes banning TikTok in the United States at this juncture, and seeks the ability to resolve the issues at hand through political means once he takes office,” his lawyer Dean John Sauer wrote in a brief to the Supreme Court.

The Supreme Court will hear oral arguments in the TikTok case on Jan. 10, and it’s expected the court will quickly rule on whether or not the law should be upheld by the time it’s due to take effect Jan. 19. It’s still unclear how the court will rule and if it will uphold a lower court ruling finding the ban is justified and does not violate TikTok’s and its users’ First Amendment rights. While Trump has asked the Supreme Court to pause the ban until after his inauguration, he isn’t a party in the litigation, and Rozenshtein told CBS News “there are no legal grounds” for Trump to demand the court pause the law since he’s still a private citizen and isn’t actually the president yet. That means there’s no guarantee the justices will listen to his request, and it’s still possible the law could take effect on Jan. 19 before Trump takes office.

Another move Trump could technically make if the TikTok ban takes effect is to say his Justice Department just won’t enforce the ban, inviting companies like Apple and Google to leave the app up on its app stores without facing the harsh financial penalties that the law imposes. But that’s unlikely to work, as legal experts have noted companies would likely comply with the ban anyway, rather than risk facing penalties if Trump ever changed his mind.

TikTok and ByteDance so far haven’t shown any interest in separating, with TikTok arguing in a court filing that doing so is “not possible technologically, commercially, or legally.” It remains to be seen if the company will change its mind should the Supreme Court uphold the law and it actually take effect, however. Trump could also potentially have an impact on forcing ByteDance’s hand, as James Lewis, director of the Strategic Technologies Program at the Center for Strategic and International Studies, told NPR that China could be persuaded to approve of ByteDance selling TikTok in exchange for Trump backing off his threat of high tariffs on Chinese imports.

The full impact of the TikTok ban taking effect is still unclear. The law does not ban Americans from using TikTok and wouldn’t wipe it from users’ phones, but rather bans U.S. app stores and internet service providers from hosting it. That means TikTok may not immediately stop working for its more than 170 million U.S. users. But it would mean that users could not download or update TikTok from Apple or Google’s app stores, it would grow obsolete and eventually no longer work. Oracle also wouldn’t be allowed to host TikTok’s U.S. user data, as it does now. It remains to be seen what the effects of that will be in practice: While TikTok said in a court filing that banning internet service providers from hosting the app means the company could no longer “provid[e]

Yes, the ban is expected to similarly impact ByteDance-owned apps CapCut and Lemon8.

If the ban does take effect and block TikTok’s U.S. user data from being hosted by a U.S. company, it’s possible the data that TikTok already has on its American users could be moved to China, which a Forbes investigation found is what happened when India similarly banned the app. That would actually make it more likely the data could be accessed by the Chinese government, contrary to the federal law’s national security goals.

President Joe Biden signed the bill requiring TikTok to leave ByteDance or else be banned into law in April, reflecting a bipartisan concern from lawmakers that the app poses a threat to national security. TikTok has long denied any wrongdoing or links to the Chinese government, but Forbes has reported numerous concerns involving the app, including TikTok spying on journalists, promoting Chinese propaganda that criticized U.S. politicians, mishandling user data and tracking “sensitive” words. The specific evidence the government has for justifying TikTok’s ban has not been made public, however, and was entirely redacted in court filings. TikTok and creators on the app sued to block the law days after it was enacted, arguing the ban unlawfully infringed on their First Amendment rights. A panel of federal judges sided with the government’s argument that the ban was justified due to the national security threat and did not violate TikTok’s First Amendment rights, given that users can still post on the app if it just separates itself from ByteDance. The court ruled the law as it was enacted is actually a less restrictive way of handling the government’s concerns about TikTok, given the fact it still allows the company to operate in the U.S. if ByteDance divests from it. TikTok appealed the case to the Supreme Court after the lower court declined to pause the law from taking effect, and the Supreme Court quickly took it up, scheduling arguments for Jan. 10 but declining to pause the law in the meantime.