The US Supreme Court refused to rescue TikTok on Friday from a law that requires the popular short-video app to be sold by its Chinese parent company, ByteDance, or banned on Sunday in the United States on national security grounds — a major blow to a platform used by nearly half of all Americans.

The justices unanimously ruled that the law, passed by an overwhelming bipartisan majority in Congress last year and signed by Democratic President Joe Biden, did not violate the US Constitution's First Amendment protection against government abridgement of free speech. TikTok, ByteDance, and some of the app's users challenged the measure, prompting the justices to uphold a lower court's decision.

"There is no doubt that, for more than 170 million Americans, TikTok offers a distinctive and expansive outlet for expression, means of engagement, and source of community. But Congress has determined that divestiture is necessary to address its well-supported national security concerns regarding TikTok's data collection practices and relationship with a foreign adversary," the court said in the unsigned opinion.

The court added, "We conclude that the challenged provisions do not violate the petitioners' First Amendment rights."

The case pitted free speech rights against national security concerns in the age of social media.

White House Press Secretary Karine Jean-Pierre on Friday reiterated Biden's position that "TikTok should remain available to Americans, but simply under American ownership or other ownership that addresses the national security concerns identified by Congress in developing this law."

Given the timing, Jean-Pierre added, action to implement the law "must fall to the next administration."

Trump's team did not immediately respond to requests for comment.

TikTok also did not immediately respond to a request for comment. TikTok plans to shut down US operations of the app on Sunday barring a last-minute reprieve, people familiar with the matter told Reuters on Wednesday. (Reuters)