White House trade advisor Peter Navarro dubbed TikTok's new CEO Kevin Mayer, an "American puppet" for working at the Chinese-owned social media app.
In an interview with Fox News on Sunday, Navarro also doubled down on accusations that Chinese apps are gathering data on Americans and handing that over to Beijing. He also said to expect "strong action" from President Donald Trump on TikTok and other Chinese apps.
TikTok has been in the crosshairs of Washington for some months. But pressure on TikTok, which is owned by Beijing-based Bytedance, rose last week when Secretary of State Mike Pompeo said the government is "looking at" banning the viral app.
The Trump administration maintains that TikTok and other Chinese apps gather lots of data from American users and send it back to China, accusations repeated by Navarro.
"What the American people have to understand is all the data that goes into those mobile apps that kids have so much fun with and seem so convenient, it goes right to servers in China, right to the Chinese military, the Chinese Communist Party, and the agencies that want to steal our intellectual property," Navarro told Fox.
"Those apps can be used to steal personal and financial information for blackmail and extortion, they can be used to steal business intellectual property and proprietary secrets."
Beijing responded with strong words to Navarro's claims.
"Who was speaking this time, Peter Navarro the White House official, or Ron Vara the fictional expert?" China's foreign ministry spokesperson Hua Chunying said.
"He claimed that those data went directly to servers in China, to the Chinese military, to the Chinese Communist Party. Then prove it. If he cannot, then it is just the latest entry into his book of shameless lies," Hua added.
"TikTok and WeChat are the biggest forms of censorship on the Chinese mainland, and so expect strong action on that," he said.
TikTok does not operate within mainland China. Instead, ByteDance runs a similar product called Douyin.
After mentioning that India banned several Chinese apps, Navarro said: "TikTok, WeChat, I suspect the president is just getting started with those two," without elaborating if that meant a ban was coming.
In response to Navarro's comments, a TikTok spokesperson said protecting the privacy of its users' data is a "critical priority."
"Our Chief Information Security Officer has decades of industry and US law enforcement experience. TikTok's parent is a privately owned company backed by some the best-known US investors, which hold four of its five board seats," a TIkTok spokesperson told CNBC.
"TikTok is enjoyed by users throughout the world, but the app is not even available in China. As we have said repeatedly, we have never shared TikTok user data with the Chinese government, and would not do so if asked. Period."
Tencent declined to comment.
TikTok has faced accusations of censorship in the past but has denied it removes "content based on sensitivities around China or other governments." In regards to privacy, TikTok has previously said that U.S. user data is stored in the United States, with a backup in Singapore. The app also said it has "never provided user data to the Chinese government" nor would it do so if asked.
Services operating on the Chinese mainland, including WeChat, regularly censor posts and messages that are deemed sensitive to the Chinese government.
TikTok has been trying to distance itself from its Chinese parent company.
ByteDance hired Mayer, a former Disney executive, to be TikTok's CEO earlier this year. His priority was seen as rebuilding trust with regulators.
But Navarro criticized the hire, calling Mayer an "American puppet" and saying that the strategy of putting a U.S. citizen in charge is "not going to work."
TikTok was not immediately available for comment specifically on the remarks regarding Mayer.
The White House trade advisor also said that any plans to spin off TikTok into an American company would not be beneficial to the U.S.
"If TikTok, if it separates as an American company, that doesn't help us because ... we're going to have to give China billions of dollars for the privilege of having TikTok operate on U.S. soil," Navarro said.
Clarification: This story has been updated to reflect that Navarro made his comments on Fox News. A previous version misstated the channel due to an editing error.