TikTok has filed a federal lawsuit against Montana after the state passed a law last week intended to ban the app from being downloaded within its borders.

The widely expected lawsuit argues that banning a hugely popular social media app amounts to an illegal suppression of free speech tantamount to censorship.

The Montana law "unlawfully abridges one of the core freedoms guaranteed by the First Amendment," the suit claims.

Lawyers for Chinese-owned TikTok also argue that the national security threat raised by officials in Montana is not something that state officials can attempt to regulate, since foreign affairs and national security matters are a federal issue.

The suit seeks to have the Montana law, which has not gone into effect yet, overturned. Last week, TikTok creators filed the first challenge to the law, saying it violates free speech rights.

TikTok is owned by the Chinese internet company ByteDance. The company says it has 150 million users in the U.S.

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

The suit calls Montana's concerns that Chinese officials could access Americans' data and subject minors to harmful content baseless.

"The state has enacted these extraordinary and unprecedented measures based on nothing more than unfounded speculation," according to the suit.

TikTok has launched what it calls Project Texas in response to the theoretical concerns about the Chinese government potentially using the app to harvest data on Americans, and even spy on U.S. citizens. The $1.5 billion data-security plan, created in collaboration with Austin-based software company Oracle, would keep Americans' data stored on U.S. servers and be overseen by an American team, TikTok says.

TikTok's Chinese ownership has set off legal fights in both the Trump and Biden White House. Right now, Biden administration officials are weighing what to do next after threatening a nationwide ban unless TikTok finds an American buyer.

While TikTok's future in the U.S. remains uncertain, most national security experts agree that scrutinizing TikTok's ties to China is warranted.

Under Chinese national intelligence laws, any organization in the country must give up data to the government when requested, including personal information about a company's customers. And since ByteDance owns TikTok, it is likely that the video-sharing app would abide by these rules if the Chinese government sought information on U.S. citizens.

Yet the fears so far remain hypothetical. There is no publicly available example of the Chinese government attempting to use TikTok as an espionage or data collection tool.

TikTok has admitted that some employees based in China have used the app to track U.S. journalists who reported on company leaks. Those employees have been fired, the company has said, and TikTok officials claim that its new data security plan would prevent such a scenario from happening in the future.

In Montana, the law signed by Gov. Greg Gianforte was met with criticism from groups including the American Civil Liberties Union and digital rights advocacy groups, which argue the law impinges on Americans' free speech rights.

Cybersecurity experts have said implementing the law would be challenging.

The law puts the onus on companies like Apple and Google, which control app stores, calling for fees up to $10,000 a day against those companies, and TikTok, if the app is available for download within the state of Montana once it takes effect in January 2024.

But experts say any such prohibition would be riddled with loopholes, and even affect residents who live outside of Montana and reside near the state's border.