The White House has threatened to make China's biggest smartphone app the latest front in its technology war with Beijing, warning of a crackdown on the text message service WeChat.
Peter Navarro, Donald Trump's trade advisor, said that the US was planning "strong action" against WeChat, a so-called "super app" owned by the Chinese internet behemoth Tencent and used by more than a billion people worldwide.
It comes days after the US raised the prospect of banning TikTok, the social media sensation owned by China-based ByteDance.
"[TikTok] and WeChat are the biggest forms of censorship on the Chinese mainland, and so expect strong action on that," Mr Navarro told Fox Business.
"What the American people have to understand is all of 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 which want to steal our intellectual property."
WeChat is a portal for a large portion of digital life in China, comprising messaging, games, payments and taxi-hailing. Conversations are censored and monitored by the Chinese government, and are not encrypted in the same way that many Western messaging apps are.
Outside of the country, the service is much more limited and less popular compared to WhatsApp, iMessage and Facebook Messenger. It is largely used by the Chinese diaspora and others to communicate to people within China.
However, the app has been viewed with suspicion in several countries. Members of the Australian military have been ordered to remove it from their phones. Last month, India banned dozens of Chinese apps including WeChat and TikTok.
Messages in the app are not censored outside of China, but researchers have claimed that the company monitors communications in the West to improve the way it censors them inside its home country. The US has grown increasingly wary of Chinese surveillance in recent years, taking aggressive action against Huawei and pressuring allies including the UK to do the same.
While it is unclear what action the US might take about WeChat, Mike Pompeo, the US Secretary of State, indicated last week that TikTok could be banned completely.
Heavy-handed action against WeChat would put Tencent, one of China's biggest tech companies, in a difficult position. The company has a string of US investments, including stakes in Snapchat, Tesla and Reddit, and its music arm is listed in New York. The company did not comment.
Last week, US bank Wells Fargo told staff to remove TikTok from their phones, while Amazon said a similar message to its employees was sent in error. Several government departments have also banned the app.