Facebook reportedly built a censorship tool for a possible return to China

Facebook has developed technology that could finally make its service palatable to Chinese authorities, who have blocked it since 2009.

The social network giant has quietly built a tool for blocking certain posts from showing up in feeds of users in some regions, according to a report from the New York Times, citing anonymous sources. CEO Mark Zuckerberg is reportedly a strong supporter of the tool, which could be used to censor politically sensitive content in China.

Facebook would delegate control over which content to suppress to a third-party, most likely a Chinese business partner, according to the report. The partner would be able to see which stories or content users are sharing and then decide whether those posts should show up in Chinese users’ feeds.

While software for the tool can be seen by Facebook employees on their internal system, it’s still merely one of many experiments the company has considered as part of a push to get into China and may never be officially released, notes the report. Some employees who worked on the tool have since left Facebook after expressing concerns about the project.

Rumors of this tool come at a particularly awkward time for Facebook. The company has been heavily criticized since the recent U.S. presidential election for failing to curtail the spread of false news articles on its network about the candidates. Initially, the company defended itself by saying that it’s merely a technology company and that it doesn’t want to police what users post and share. However, Facebook has since softened its stance by saying it would explore ways to cut back on fake news.

Facebook’s development of censorship tools is driving at least partly by the potential riches of reentering China.

“We have long said that we are interested in China, and are spending time understanding and learning more about the country. However, we have not made any decision on our approach to China,” a Facebook spokesperson told Fortune in a statement. “Our focus right now is on helping Chinese businesses and developers expand to new markets outside China by using our ad platform.”

The story has been updated with a statement from Facebook.

This story originally appeared on Fortune.com. Copyright 2016