A U.S. Senate subcommittee has launched an investigation into Meta Platforms’ (META, Financial) historical initiatives to establish a presence in China, according to a Reuters article.

The Permanent Subcommittee on Investigations — led by Senator Ron Johnson, with support from Senators Richard Blumenthal (Trades, Portfolio) and Josh Hawley — has formally requested internal documentation from Meta.

The senators directed a letter to Chief Executive Mark Zuckerberg, referencing claims that the tech company explored developing content censorship tools potentially aligned with Chinese government demands as part of its market entry strategy.

According to the report, lawmakers have asked Meta to provide all communication records involving Chinese authorities dating back to 2014. The requested documents are due by April 21.

Reuters cited excerpts from a new book by former Facebook executive Sarah Wynn-Williams, titled Careless People, which alleges Meta once drafted a multi-year strategy called “Project Aldrin” aimed at entering China.

The senators claim their concerns are substantiated by Meta’s internal materials reviewed by the Subcommittee. They are also seeking files on Meta’s defunct apps that were trialed in China — such as Colorful Balloons and MSQRD — and any involvement in a now-abandoned undersea cable link to Hong Kong.

Meta told Reuters that the allegations stem from a former employee dismissed in 2016. The company acknowledged it had explored access to China but ultimately abandoned those plans.

It’s important to note that shares of Meta rose over 1% in pre-market trading Wednesday.