Twitter and Facebook have uncovered and suspended a network of fake accounts that were believed to have been operated by the Chinese government. On Monday, both companies disclosed their investigations into the coordinated information operation, which was apparently intended to sow political discord around the protests taking place in Hong Kong.

According to Twitter, 936 accounts created within the People’s Republic of China were found to be “deliberately and specifically” sowing discord in Hong Kong in an attempt to undermine “the legitimacy and political positions of the protest movement on the ground.”

“All the accounts have been suspended for a range of violations of our platform manipulation policies,” Twitter said in the blog.

The network discovered by Facebook was smaller. According to Nathaniel Gleicher, Facebook’s head of cybersecurity policy, seven pages, three groups, and five accounts traced back to China were removed after being found to have taken part in the information operation opposing the protests. About 15,500 accounts followed at least one of these pages, and 2,200 joined at least one of these groups.

Facebook and Twitter are forbidden in mainland China (but not in Hong Kong), and they’re only technically accessible to users who connect through a VPN.

Earlier this summer, protests broke out in Hong Kong opposing a Chinese bill that would allow people living within the special administrative region who are accused of crimes to be extradited to China for trial. Those protests have escalated in recent weeks, shutting down the city’s airport and filling public squares with crowds of more than a million people.

Twitter has drawn fire for accepting ads from Chinese state media in the midst of the conflict, with a number of promoted tweets from China Daily expressing similar skepticism about the protestors’ motives. In its blog post today, Twitter said it will no longer accept advertising from state-controlled media entities. Spokespeople for the platform said that state-backed media accounts will be “free to continue to use Twitter,” but their advertising abilities will be removed.

Unlike Twitter, Facebook did not announce any policy changes in response to the discovery. “We’re committed to continually improving to stay ahead,” Gleicher said. “That means building better technology, hiring more people and working more closely with law enforcement, security experts and other companies.”