Numerous Chinese-language accounts, some dormant for months or years, came to life early Sunday and started spamming the service with links to escort services and other adult offerings alongside city names.

The result: For hours, anyone searching for posts from those cities and using the Chinese names for the locations would see pages and pages of useless tweets instead of information about the daring protests as they escalated to include calls for Communist Party leaders to resign…

The campaign was spotted by researchers at Stanford University and elsewhere. Stanford Internet Observatory Director Alex Stamos said his team is working to determine how widespread and effective it is…

“Fifty percent porn, 50 percent protests,” said one U.S. government contractor and China expert, speaking on the condition of anonymity to discuss intelligence issues.