TikTok has returned to the US after the company brought its service offline on Saturday evening.

Under the outgoing Biden Administration, TikTok was designated a national security risk and banned on the eve of Trump's inauguration.

Trump TikTok
– DCD/The White House

Despite that law being technically active and upheld by the Supreme Court, Biden's administration said that it would not enforce the law and instead defer to the incoming Trump administration.

"Frankly, we have no choice. We have to save it," Trump said at a rally on Sunday. He added that the US will seek a joint venture with the company.

"I would like the United States to have a 50 percent ownership position in a joint venture," he said on Truth Social, his own social media website.

Trump previously tried to ban TikTok while he was in office, and then tried to force a sale. The US operations were set to be bought by Oracle and Walmart, but that deal fell apart when Biden came into office.

"As a result of President Trump's efforts, TikTok is back in the US," the company said in a message on its app.

Trump has promised to sign an Executive Order that "will also confirm that there will be no liability for any company that helped keep TikTok from going dark before my order," the president-elect said on Truth Social.

That would include app store operators Google and Apple, as well as cloud provider Oracle.

However, during the Supreme Court hearings, Justice Sonia Sotomayor said: "Whatever the new president does, [it] doesn't change that reality for these companies."

An executive order cannot change the law retroactively. However, the law does include a provision that would allow the president to postpone the ban for up to 90 days, if they can show that the company is making substantial progress on alleviating national security issues. It is not clear if those provisions have been met.