The U.S. Department of Justice asked a federal appeals court late on Friday to uphold an April law requiring China-based ByteDance to sell TikTok's U.S. assets by Jan. 19 or face a ban, Paralel.Az reports citing Reuters.

The DOJ argued in its filing that TikTok under Chinese ownership poses a serious national security threat because of its access to vast personal data of Americans, asserting China can covertly manipulate information that Americans consume via TikTok.

"The serious national-security threat posed by TikTok is real," the department said. "TikTok provides the Chinese government the means to undermine U.S. national security in two principal ways: data collection and covert content manipulation."

The Biden administration asked the U.S. Court of Appeals for the District of Columbia to reject lawsuits by TikTok, parent company ByteDance and a group of TikTok creators seeking to block the law that could ban the app used by 170 million Americans.

TikTok has repeatedly denied it would ever share U.S. user data with China or that it manipulates video results.

"The government has never put forth proof of its claims, including when Congress passed this unconstitutional law. Today, once again, the government is taking this unprecedented step while hiding behind secret information", TikTok posted on social media platform X in response to the DOJ brief.

The DOJ's filing details wide-ranging national security concerns about ByteDance's ownership of TikTok.

"China’s long-term geopolitical strategy involves developing and pre-positioning assets that it can deploy at opportune moments," the department said.

The government acknowledged in a separate declaration it had no information that the Chinese government had gained access to the data of U.S. TikTok users but said the risk of the possibility was too great.

"The United States is not required to wait until its foreign adversary takes specific detrimental actions before responding to such a threat," the filing said.