TikTok said it would “go dark” on Sunday unless President Joe Biden’s administration offered assurance that it would not enforce a ban upheld Friday by the Supreme Court for the app’s U.S. operations to be sold or booted over “national security concerns.

Congress last year in a law signed by President Joe Biden required that TikTok’s China-based parent company ByteDance divest the company by Jan. 19 or risk getting banned in the U.S.