The last of Facebook’s major products that still worked in China was hit by government blocks on Tuesday, as Beijing broadly tightens its controls over the internet.
WhatsApp, a messaging app used across the globe, was partly disrupted by Chinese filters, leaving many unable to send videos and photos and some also unable to send text-based messages.
The disruption of WhatsApp was the latest in a long line of big digital services running up against China’s “Great Firewall,” the country’s system of internet filters and controls. In recent weeks, the government has appeared to increase its grip, an online crackdown fed by a perfect storm of politically sensitive news, important upcoming events, and a new cybersecurity law that went into effect last month.
Sites hosting popular foreign television shows have had videos taken down, and tools used to skirt the censors have faced more frequent disruptions. In an article, the mouthpiece of the country’s Communist Party scolded the Chinese internet company Tencent over a popular video game, calling it too addictive.
The news environment has heightened the sensitivity. In recent weeks, the Chinese dissident Liu Xiaobo passed away in detention. A Chinese billionaire in the United States accused senior leaders of graft, from his platform on Twitter. And Hong Kong commemorated the 20th anniversary of its handover to China.
To make matters more fraught, the 19th Party Congress” where top leadership positions are determined ” is just months away. In the run up to the event, which happens every five years, the government puts an increased emphasis on stability, 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.
Mr. Kobeissi said it was not clear whether the targeted censorship of videos and photos was intentional, or if it was just a prelude to a more complete block of WhatsApp in the coming days.
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, it is used by many Chinese to communicate or do business outside the country or in Hong Kong.
In the past, partial blocks have sometimes led to full bans, or have eventually been removed by the government, and service restored. Still, Beijing’s track record with other American social networking services does not bode well for WhatsApp. Facebook, Instagram, Twitter, Google and Gmail are all blocked in the country.