The Supreme Court seemed inclined on Friday to uphold a law that would force a sale or ban the popular short-video app TikTok in the United States by Jan. 19, with the justices focusing on the national security concerns about China that prompted the crackdown.

The court is hearing oral arguments on TikTok’s bid to block a law that would lead to its ban in the U.S. starting Jan. 19 if it isn’t sold by its Chinese owner.

Lower courts ruled that a task force that determines which treatments must be covered at no cost had not been validly appointed.