A July 16 report from Citizen Lab, based out of the University of Toronto, reveals that images of Liu were automatically filtered in private one-on-one chats on Wechat, China’s most widely used chat app with 768 million daily active users. In other words, after being sent by one user, it disappeared and never reached the other user. It was the first time it found image deletion occurring in chats between just two people on Wechat, Citizen Lab said. The group has previously found that censorship on Wechat primarily occurs in group chats, when users attempt to send messages containing certain keywords.

This week, reports from major news outlets including the New York Times (paywall) and Bloomberg found that Facebook-acquired WhatsApp has been partially blocked in China, since earlier this week. The WhatsApp disruption also appears to be image-centric: Many WhatsApp users in China have reported that they are not able to send photos and videos, and some also unable to send text messages, according to the Times. A cryptography researcher told the Times that the Chinese censors are selectively targeting WhatsApp functionalities. WhatsApp has a relatively small user base in China, and differentiates itself from major Chinese messaging services by offering end-to-end encryption.

It is unclear whether the partial block on Whatsapp will be lifted or turn into a complete block. But the pattern of the past is clear: the Chinese government bans popular Western social-media services including Twitter, Facebook and Instagram, effectively forcing its citizens to rely entirely on Chinese equivalents—for example, the far more widely used WeChat—which are subject to censorship and are known to hand over user data to the authorities when required to do so.

But there’s a broader context too, beyond Liu. China is now only a few months from the 19th congress of the Chinese Communist Partydate to be decidedwhere major leadership appointments will be announced. That’s also a likely reason for the recent disruptions of the two chat apps–and a series of other tightened internet controls. Last week, Beijing reportedly stepped up its crackdown on VPN services, a key tool Chinese citizens depend on to get access to the unfiltered internet.

This week, a couple of international hotels, including the Waldorf Astoria in Beijing, appear to either not be offering VPN service to foreign guests or offering a restricted form of it. One hotel told Quartz it will offer something called “internet enhancement,” a tailor-made access to some selected sites beyond the Great Firewall.

Mentions of Winnie the Pooh, the popular cartoon bear, are also running into blocks on the Chinese microblogging service Weibo, as people have for years compared the fictional bear to Xi Jinping, China’s president. The upcoming congress is particularly important to Xi, as the Chinese leader, already the most powerful in three decades, may be planning on a third term beyond 2022, when he is expected to retire.

Echo Huang contributed to this article.

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