The battle in Montana erupted during a period of intense national scrutiny on TikTok, which boasts more than 150 million U.S. users. Lawmakers and intelligence officials have said TikTok, because of its ownership, could put sensitive user data into the hands of the Chinese government, pointing to laws that allow Beijing to secretly demand data from Chinese companies and citizens for intelligence gathering.

They have also expressed concern that the app, which is especially popular with teenagers and people in their 20s, could be used to spread propaganda. Congress grilled Shou Chew, TikTok’s chief executive, for roughly five hours at a March hearing that focused largely on the app’s Chinese ownership.

TikTok says it has never been asked to provide, nor has it provided, any U.S. user data to the Chinese government. The company has proposed a detailed plan for operating in the United States that it says should allay national security concerns and fears of misinformation, but the plan has not yet been approved by the Biden administration, leaving TikTok and its future in limbo.

Free speech groups were quick to respond to the Montana ban. The American Civil Liberties Union said on Wednesday that the legislation “flouts the First Amendment.”

“The government cannot impose a total ban on a communications platform like TikTok unless it is necessary to prevent extremely serious, immediate harm to national security,” the group said in a statement. “But there’s no public evidence of harm that would meet the high bar set by the U.S. and Montana Constitutions, and a total ban would not be the only option for addressing such harm if it did exist.”