TikTok on Monday sued to block Montana from banning the popular video app, escalating its efforts to stop a prohibition that would be the first of its kind in the nation.

In a lawsuit filed in U.S. District Court for the District of Montana, the company said Montana’s legislation violated the First Amendment and parts of the U.S. Constitution that limit state powers. The ban was “unconstitutionally shutting down the forum for speech for all speakers on the app,” the company said in the lawsuit.

TikTok sued days after Montana’s governor, Greg Gianforte, signed the ban — which would fine the video app if it operated in the state or app stores if they allowed it to be downloaded — into law. The state law has become a test case for whether it is possible to prohibit the use of TikTok, which is owned by the Chinese internet company ByteDance, over national security concerns. The ban, which is set to go into effect on Jan. 1, has already raised questions about how it would be enforced within Montana’s borders.

“We are challenging Montana’s unconstitutional TikTok ban to protect our business and the hundreds of thousands of TikTok users in Montana,” Brooke Oberwetter, a TikTok spokeswoman, said in a statement. “We believe our legal challenge will prevail based on an exceedingly strong set of precedents and facts.”