Among the Senators, Republican Marsha Blackburn is among the first to confirm a meeting with Zhu, following her open letter to the TikTok chief last month where she expressed concerns over how the app could help the Chinese government “gain unfettered and unsupervised access” to American children’s lives.

“Because TikTok is owned by ByteDance, the app is subject to foreign laws that allow China’s government to seize its information and technology,” she said in the letter, adding that more information is required to ensure the protection of children's privacy.

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TikTok did not immediately respond to inquiries sent via email about Zhu’s US trip.

Senator Blackburn did not immediately respond to an inquiry sent via her website.

Tech giants in the US have faced headwinds over the past year amid rising concerns over their monopoly positions and unchecked collection of user data. Google is facing an antitrust probe by 50 attorneys general in the US while Facebook is under the regulatory spotlight after massive data breaches over the past two years.

The US is TikTok’s third largest market after India and China, accounting for about 123.8 million downloads or 8.2 per cent of the total, according to Sensor Tower. The Chinese owned company says its user data is stored in Virginia, with a backup server in Singapore, and that it would never share user data with the Chinese government, or even with its parent company.

Still, the US army banned soldiers from using TikTok due to potential national security risks, according to Army Secretary Ryan McCarthy, speaking to CNBC last week. The move came after the top Democrat in the US Senate Chuck Schumer expressed concern about the US military’s use of TikTok for recruiting American teenagers.

In an interview with The New York Times last month, Zhu said the app would never censor videos that displeased the ruling Communist Party. When asked what he would do if Chinese leader Xi Jinping personally asked the company to take down a video or hand over user data, Zhu replied: “I would turn him down.”

However, doubts resurfaced less than two weeks later after a US teenager complained about losing access to her account after posting a video critical of the Chinese government’s treatment of Uygur Muslims in Xinjiang. The company first attributed the penalty to a previous video she had posted, but later acknowledged it was due to a “human moderation error”.

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“Ample and growing evidence exists that TikTok’s platform for western markets, including the US, are censoring content in line with China’s communist government directives,” Marco Rubio said in a tweet in October, as the Senator from Florida urged the CFIUS committee to review ByteDance’s acquisition of Musical.ly, an app popular among Generation Z that allowed them to lip-synch to popular songs.

The US is uncharted territory for most Chinese tech giants, especially in social media. TikTok has been the first Chinese-developed app to take the world by storm, reinforcing its global position after its merger with Musical.ly and a rebranding in August 2018.

“The regulation of content is always the first thing for content products, whether it’s in the domestic market or overseas. [Companies] have to follow the local market rules to regulate their data,” said Xue Yu, research manager at IDC China’s Industry and New Technology Research Department, who compared TikTok’s scrutiny to that given to Huawei after it became successful in selling telecoms equipment to US carriers and began promoting its leadership in 5G networks.

“I don’t think there is anything special [about TikTok's situation in the US]. It is easy to link it with what happened with Huawei and ZTE previously. TikTok had a very enthusiastic response in the market, so it will lead to [negative attention from the US],” he said.

TikTok has reached 1.5 billion total downloads on the App Store and Google Play, according to Sensor Tower. It is the third most downloaded non-gaming app of the year after WhatsApp and Messenger.

The ubiquitous app uses an AI model to track user behaviour and tailor content on their personalised page, so gaming addicts will receive more gaming-related videos while music lovers will see more music-related videos.

ByteDance is hiring new positions for its trust and safety team, according to people familiar with the matter, who spoke to the Post last month. New openings were shown on its website in Mountain View, California, as well as Singapore and Dublin, Ireland.

“The geopolitical battle cannot be ignored. TikTok needs to tread carefully given the significant growth opportunities outside Asia,” said Paolo Pescatore, a London-based analyst at PP Foresight. “It is proving to be a key destination for many people around the world, driving engagement which can open up new revenue opportunities.”