Montana Gov. Greg Gianforte signed a bill Wednesday banning TikTok in the state. Gianforte tweeted that he has banned TikTok in Montana “to protect Montanans’ personal and private data from the Chinese Communist Party,” officially making it the first state to ban the social media application. The controversial law marks the furthest step yet by a state government to restrict TikTok over perceived security concerns and comes as some federal lawmakers have called for a national ban of TikTok. But it is expected to be challenged in court. The bill, which will take effect in January, specifically names TikTok as its target, prohibiting the app from operating within state lines. The law also outlines potential fines of $10,000 per day for violators, including app stores found to host the social media application. Last month, lawmakers in Montana’s House of Representatives voted 54-43 to pass the bill, known as SB419, sending it to Gianforte’s desk. In a statement to CNN, TikTok said it would push to defend the rights of users in Montana. “Governor Gianforte has signed a bill that infringes on the First Amendment rights of the people of Montana by unlawfully banning TikTok, a platform that empowers hundreds of thousands of people across the state. We want to reassure Montanans that they can continue using TikTok to express themselves, earn a living, and find community as we continue working to defend the rights of our users inside and outside of Montana.” The law comes as TikTok faces growing criticism for its ties to China. TikTok is owned by China-based ByteDance. Many US officials have expressed fears that the Chinese government could potentially access US data via TikTok for spying purposes, though there is so far no evidence that the Chinese government has ever accessed personal information of US-based TikTok users. NetChoice, a technology trade group that includes TikTok as a member, called the Montana bill unconstitutional. “The government may not block our ability to access constitutionally protected speech – whether it is in a newspaper, on a website or via an app. In implementing this law, Montana ignores the U.S. Constitution, due process and free speech by denying access to a website and apps their citizens want to use,” said Carl Szabo, NetChoice’s general counsel. The ACLU also pushed back on the bill, releasing a statement saying that “with this ban, Governor Gianforte and the Montana legislature have trampled on the free speech of hundreds of thousands of Montanans who use the app to express themselves, gather information, and run their small business in the name of anti-Chinese sentiment.” On Wednesday, Gianforte signed a separate executive order that prohibits the use of any social media application “tied to foreign adversaries” on government devices, including ByteDance-owned CapCut and Lemon8, and Telegram Messenger, which was created while the founder lived in Russia, but is based in Dubai. Update: This story has been updated to clarify Telegram’s origins.