WhatsApp has been widely blocked in mainland China by the country’s government, with text messaging as well as photo and video sharing not currently functional. However, WhatsApp had previously been blocked in the country and saw those blocks lifted within a few days, so it’s unclear how long the chat app may remain inaccessible.

The New York Times reported today that WhatsApp had been “broadly disrupted in China.” TechCrunch has received reports that while many users lost access beginning Sunday night, some in mainland China can still send and receive WhatsApp messages. WhatsApp declined to comment on the blockage.

WhatsApp’s ability to send videos, photos and files was blocked in China in July, but allowed again a few weeks later.

It’s possible that the shut down is in anticipation of the Communist Party’s congress to be held in Beijing next month. WhatsApp may have been targeted because of its strong encryption features lacked by services like Skype and Apple’s FaceTime that are allowed to operate in China. Encrypted messaging could be used by political dissidents organizing against the government.

If the ban is lifted, it could serve as a show of power by the Chinese government, and might dissuade users seeking to rely on an encrypted messaging service in the country. But if the ban is left in place, it could disrupt businesses that rely on WhatsApp to communicate with customers. It would also be a big step back for parent company Facebook’s relations with China.

Facebook has long been banned in mainland China, like other foreign social media broadcasting services. But Facebook was discovered to have built a Chinese version of its private photo-sharing app (Moments) in China, called Colorful Balloons, distributed under the inconspicuous company name Youge Internet Technology. It’s unclear whether the Chinese government was aware that Facebook was behind the app prior to The New York Time’s expose.

Facebook reportedly built a censorship tool last year that could be applied to its main social network, which could appeal to Chinese regulators who currently maintain a ban on Facebook in the country. But the Colorful Balloons situation, the July partial ban of WhatsApp and today’s blockage could signal that Facebook’s relationship with China is fraying rather than strengthening.

As Facebook hits use growth saturation in many parts of the world, China remains an untapped opportunity for growth. The company has long held that partial access to its services, even with censorship, is better than no access, as it can connect people to loved ones and knowledge that can help them improve their lot in life. But working with censors and a government known for hostility toward human rights activists could force Facebook to contradict some of its values or leave dissidents vulnerable.

Given Facebook’s tricky situation at home in the U.S. as it deals with fake news and election interference initiated by Russian operatives, it may not have the bandwidth to focus on furthering relations with China.