A recent report from the Wall Street Journal alleges that the Chinese-owned social media app TikTok circumvented a privacy safeguard in Google’s Android operating system to collect user data.

The Wall Street Journal reports that the Chinese-owned social media app TikTok, which has come under fire from the Trump administration over national security concerns, circumvented a privacy safeguard in Google’s Android operating system to collect unique identifiers from millions of users that would allow the app to track users online without letting them opt-out.

Mobile-phone security experts told the WSJ that the tactic used by TikTok was concealed through an unusual added layer of encryption, very likely violated Google policies relating to how apps track people, and was not disclosed to Twitter users. TikTok stopped the tracking practice in November according to tests performed by the WSJ.

The TikTok app collected unique device identifiers called MAC addresses, these are commonly used for advertising purposes. The Trump administration has previously expressed concerns over how TikTok users’ data is collected and whether or no it could be obtained by the Chinese government and used for blackmail or espionage.

TikTok claimed earlier this year that it collects less personal data than Silicon Valley tech giants such as Facebook and Google, but didn’t respond to the WSJ’s detailed questions about its collection of user data. A spokesperson stated that TikTok is “committed to protecting the privacy and safety of the TikTok community. Like our peers, we constantly update our app to keep up with evolving security challenges.”

The company added that “the current version of TikTok does not collect MAC addresses.” Most mobile apps collect user data, but tech firms have defended their collection of user data by stating that it helps them to provide customized experiences and targeted advertising to users.

Joel Reardon, an assistant professor at the University of Calgary and cofounder of AppCensus, Inc., commented on TikTok’s collection of MAC addresses stating: “It’s a way of enabling long-term tracking of users without any ability to opt-out. I don’t see another reason to collect it.”

Read the full report at the Wall Street Journal here.

Lucas Nolan is a reporter for Breitbart News covering issues of free speech and online censorship. Follow him on Twitter @LucasNolan or contact via secure email at the address lucasnolan@protonmail.com