TikTok, a popular social media platform owned by Chinese tech company ByteDance, has gone dark in the United States, with a law banning its use taking effect on Sunday, a move experts said will increase uncertainties and bring unprecedented operational challenges for the video-sharing app in the country.

In a message to users on Saturday night, TikTok said the app would be "temporarily unavailable", and the company is working to restore its US service "as soon as possible".

The app has been removed from prominent app stores, including the ones operated by Google and Apple. Other apps owned by ByteDance, including lifestyle-sharing platform Lemon8 and video-editing platform CapCut, are also currently unavailable in US app stores.

Meanwhile, US President-elect Donald Trump said on Saturday that he was thinking about giving TikTok a 90-day extension.

"I think that would be, certainly, an option that we look at. The 90-day extension is something that will be most likely done, because it's appropriate," Trump told NBC News in a phone interview.

If such an extension is granted, Trump, who once favored a TikTok ban, said it would "probably" be announced on Monday, the day he is sworn in as president.

The TikTok blackout came as the US Supreme Court upheld on Friday a law requiring ByteDance to sell the app to a US company or face a nationwide ban starting on Sunday.

TikTok CEO Shou Zi Chew posted a video thanking Trump for his commitment to work with the company to keep the app available in the US, saying that "this is a strong stand for the First Amendment and against arbitrary censorship".

Trump, who issued an executive order to ban TikTok during his first term in office, opened an account on the app during his 2024 presidential campaign to connect with young voters.

Zhu Keli, founding director of the China Institute of New Economy, said the decision to uphold the ban casts a shadow on TikTok's future in the US, but Trump's "most likely" 90-day extension could provide a valuable buffer period for the company.

"Trump's stand indicates that TikTok still has a chance to seek a better solution to ensure its legal operation in the US through negotiation, cooperation or other innovative methods. It is also a recognition of TikTok's immense user base and commercial value," Zhu said.

Zhu noted that the TikTok case highlights the compliance challenges that Chinese tech companies are facing, especially in terms of data security, when expanding their presence in overseas markets amid rising geopolitical uncertainties.

After the court ruling, the White House said the Biden administration would leave the implementation of the ban to Trump. But TikTok said on Friday evening that it "will be forced to go dark" if the administration didn't provide a "definitive statement" to the companies, such as Apple, Google and Oracle, that deliver its services in the US.

Zhou Mi, a researcher at the Chinese Academy of International Trade and Economic Cooperation in Beijing, said the suspension of TikTok's services will have an impact on the confidence of its millions of users in the US, underscoring the significance of conforming to local regulatory requirements in overseas markets and paying attention to user data management to mitigate potential compliance risks.

TikTok has worked on an initiative called "Project Texas" by storing US-based user data in the servers of US tech company Oracle to address the US government's concerns about data security.