In response to widespread pro-democracy demonstrations in Hong Kong, the Chinese government launched an online disinformation campaign casting the protesters as members of ISIS and cockroaches, according to disclosures made by Twitter and Facebook on Monday. Since the two social networks are blocked on mainland China, the propaganda efforts appear designed to influence perception of the protests overseas. Solidarity demonstrations backing Hong Kong have taken place around the world in recent weeks, and some have been met by counterprotests supporting Beijing.

Twitter announced Monday it had removed over 900 accounts it believes were established by the Chinese government, which were “deliberately and specifically" attempting to sow political discord and undermine "the legitimacy and political positions of the protest movement on the ground.” The accounts were part of a much larger network of around 200,000 accounts Twitter took down before they were "substantially active" on the service.

Facebook's head of cybersecurity policy Nathaniel Gleicher said in a blog post that the company had similarly removed five Facebook accounts, seven pages followed by a total of around 15,500 people, and three groups with a combined 2,200 members that an investigation found had links to the Chinese government.

One of the Facebook posts Facebook believes originated from China.

Both Twitter and Facebook also ran paid advertisements from Chinese state-run media agencies like China Daily, Xinhua News, and CGTN, which discredited the protesters or painted them as disruptive, according to investigations from Buzzfeed News and Gizmodo. After the reports came out, Twitter announced it would no longer accept advertising from “state-controlled news media entities.”

A spokesperson for Twitter said the policy changes had been in the works for a while, and were not a direct response to the Chinese ads. Two years ago, after it was discovered the Russian government had crafted a misinformation campaign intended to influence the 2016 US presidential election, Twitter restricted Russian state-owned news outlets RT and Sputnik from advertising on its platform. The social network said at the time that the ban would not apply to other advertisers.

Twitter’s new policy won’t affect “taxpayer-funded entities,” including public broadcasters like NPR in the US and the BBC in the UK, as well as outlets that are solely dedicated to entertainment, sports, and travel coverage. The Twitter spokesperson also said that Voice of America, a US state-owned media organization primarily viewed by foreign audiences, is also exempt, since it has independent oversight.