To complicate matters, the 19th Party Congress — where top leadership positions are determined — is just months away. The government puts an increased emphasis on stability in the run up to the event, which happens every five years, often leading to a tightening of internet controls.
WhatsApp, which had generally avoided major disruptions in China despite the full block of Facebook and Instagram, appears to have become a victim of those circumstances.
The blocks against WhatsApp originated with the government, according to a person familiar with the situation who declined to be named because they were not authorized to speak on the record about the disruption. Security experts also verified that the partial disruption in WhatsApp started with China’s internet filters.
“According to the analysis that we ran today on WhatsApp’s infrastructure, it seems that the Great Firewall is imposing censorship that selectively targets WhatsApp functionalities,” said Nadim Kobeissi, an applied cryptographer at Symbolic Software, a cryptography research start-up.
The actions by the Chinese government are another setback for Facebook in a country that has been difficult for the world’s largest social network to crack. Its flagship site was blocked in 2009 after ethnic unrest in western China; Instagram followed in 2014 during protests that fall in Hong Kong.
Beginning in late 2014, Facebook began an aggressive campaign to woo the Chinese government and get its main social network back into the country. As part of the courtship, Facebook’s founder, Mark Zuckerberg, showed off his language chops at a conference and later dined with President Xi Jinping during a state visit to the United States.
But Facebook’s efforts have slowed over the past year, and it has little to show for itself. Instead of getting a new product into China, the internet giant now faces the reality that its last app standing is under threat of being pushed outside the walls of Chinese censorship.
A spokeswoman for WhatsApp declined to comment.
Since taking power almost five years ago, Mr. Xi has presided over a consistent and deepening suppression of internet freedom. He has been vocal in calling for China to establish sovereignty online, and has set up a new internet regulator to consolidate controls over the web.
The scale of the recent actions shows the increasing muscle of the Chinese government, which has strengthened this year.
In recent months, a number of virtual private networks, tools that allow users in China to access the broader internet around the world, were removed from app stores or shut down. China’s telecom regulator said it would ban unauthorized VPNs starting in February 2018.
The new cybersecurity rules, broad and vague, have left Western companies uncertain of how they will be applied and what impact they could have on a difficult operating environment. The government has put strong emphasis on the law, which could serve as a watershed for how the internet is managed and foreign companies are policed.
This month, Apple opened its first data center in China. The company said the move was made to comply with the law that calls for companies to store their data in China.
The disruption of encrypted messaging programs like WhatsApp and censorship circumvention tools like VPNs shows a desire to take almost total control over how the internet is used.
WhatsApp is hugely popular around much of the globe, but the platform is not widely used in China, where local messaging app WeChat dominates. Even so, WhatsApp provides encrypted messaging, making it a useful tool for many Chinese to communicate or do business outside the country or in Hong Kong.
Paul Triolo, the head of geo-technology at Eurasia Group, said that a possible next step would be for China to target other encrypted messaging apps like Signal, pointing out that such apps “represent a small but growing and potentially important hole in the Great Firewall.”
“The ministries and support organizations that undergird the Great Firewall must constantly prove they can keep abreast of technological change, and encrypted messaging apps are just the latest in a long string of innovations that have drawn the attention of the technical wizards behind the Great Firewall,” Mr. Triolo said.
The apparent crackdown is part of the jockeying among Chinese ministries ahead of this autumn’s congress to show that they are doing their job, according to a government tech policy adviser who declined to be named because of possible retribution over speaking to foreign news media. While there is a real push to make it harder to use VPNs, he said the new rules set to take effect next year are unlikely to be so extreme that they entirely prevent individuals from being able to use such tools.
Some in the Chinese government are worried that the excess censorship and controls are damaging the country’s ability to access crucial information, like scientific papers and other educational resources. As such, there have been calls for a more surgical way to block specific material, rather than a sledgehammer approach that takes out entire services.
In the case of WhatsApp, it is not clear whether the targeted censorship of videos and photos was intentional, or if it was just a prelude to a more complete block. Previous partial blocks have sometimes led to full bans, or they have eventually been removed by the government, and service restored.
Beijing’s track record with other American social networking services does not bode well for WhatsApp. Besides Facebook and Instagram, Twitter, Google and Gmail are all blocked in the country.
“It’s like when Gmail first got throttled, the blockage was very uneven,” said Lokman Tsui, a professor at the School of Journalism and Communication at the Chinese University of Hong Kong.