Chinese video service TikTok has begun a legal challenge against the Trump administration over plans to shut it down in the US on 12 November.
President Donald Trump ordered a ban on new downloads of the viral video service on that date unless ByteDance was purchased by a US firm.
TikTok said it had worked since August attempting to comply with the order, issued amid security concerns.
It said it had had no feedback from the US government in two months.
"TikTok has actively engaged with CFIUS (Committee on Foreign Investment in the United States) in good faith to address its national security concerns, even as we disagree with its assessment," the firm said in a statement.
"In the nearly two months since the president gave his preliminary approval to our proposal to satisfy those concerns, we have offered detailed solutions to finalise that agreement but have received no substantive feedback on our extensive data privacy and security framework."
That included a new proposal that would "create a new entity wholly owned by Oracle, Walmart and existing US investors in ByteDance, that would be responsible for handling TIkTok's US user data and content moderation".
It added that it had filed a court petition with the US Appeals Court to "defend our rights and those of our more than 1,500 employees in the US".
It is seeking a court review of the original order and a 30-day extension on discussions.
The political landscape has obviously changed since August, and with Joe Biden winning the presidency and due to take over in January, TikTok is likely to be questioning whether he will have a different approach to Chinese firms working in the US.
A potential deal which would have seen ByteDance agree to sell part of its US business to Oracle and Walmart has never been approved by the Chinese government, despite a tentative green light from President Trump.