Facebook has sued four Chinese companies for selling fake Facebook and Instagram accounts, alleging trademark infringement, breach of contract, and related offenses. The company announced the news on Friday, calling it “one more step in our ongoing efforts to protect people on Facebook and Instagram.” It’s an unusual move for Facebook, which says it already purges “millions” of fake accounts every day.

The lawsuit names three people and four companies based in the cities of Longyan and Shenzhen: 9 Xiu Network (Shenzhen) Science and Technology Company, 9 Xiu Feishu Science and Technology Company, 9 Xiufei Book Technology Co., and Home Network (Fujian) Technology Co.

According to the complaint, these companies offer a variety of hardware and software services including bundles of fake accounts for Facebook and Instagram as well as other platforms like Twitter, Snapchat, YouTube, LinkedIn, and Google Voice. They also allegedly advertise services “designed to increase likes, comments, friends, and other activity,” and they’ve promoted themselves with the made-up label “Facebook China Regional Strategic Partner,” offering premium accounts that supposedly couldn’t be suspended. The complaint names several websites, all of which appear to be offline, although TechCrunch says they were mostly functional when the lawsuit was filed on March 1st.

Facebook and Instagram deleted 2.1 billion fake accounts over nine months

Facebook says these companies improperly used its trademarks and violated cybersquatting laws with confusingly named web addresses like “myfacebook.cc,” “facebook88.net,” and “infacebook.cc.” Since Facebook and Instagram’s terms of service prohibit fake accounts, it’s also suing for breach of contract. It’s asking the court to ban the companies from creating misleading sites or fake accounts and to award Facebook all of the profits made from these accounts plus $100,000 for each infringing domain name.

Fake accounts are a perennial problem for Facebook. The complaint says Facebook and Instagram disabled 2.1 billion fake accounts between January and September 2018. “By filing the lawsuit, we hope to reinforce that this kind of fraudulent activity is not tolerated – and that we’ll act forcefully to protect the integrity of our platform,” Facebook says in its statement.

This isn’t the first lawsuit regarding fake accounts and online engagement. Amazon has sued people who allegedly spam pages with five-star ratings, and government agencies have recently started going after companies that buy or sell fake accounts and reviews. In January, New York’s attorney general announced a settlement with Twitter bot company Devumi. In February, the Federal Trade Commission settled a complaint with Cure Encapsulations, which paid a company to post reviews about a potentially dangerous (and ineffective) weight-loss supplement.

But Devumi and Cure Encapsulations both operated inside the US, and so did at least some of Amazon’s targets. Facebook may have a harder time fighting these overseas companies, especially because China has consistently blocked Facebook from operating within its borders. Chinese internet censors have filtered the platform for nearly a decade, and the government aborted a short-lived deal to open a local subsidiary last year. But whatever the outcome, Facebook is normalizing the notion that selling fake accounts will get companies in legal trouble.