The company took down 936 accounts that originated within China.

“Based on our intensive investigations, we have reliable evidence to support that this is a coordinated state-backed operation,” the company said Monday in a blog post. “Overall, these accounts were deliberately and specifically attempting to sow political discord in Hong Kong, including undermining the legitimacy and political positions of the protest movement on the ground.”

Twitter said it also is going to stop accepting advertising from state-backed media worldwide, after finding propaganda messages that Chinese-run media paid to promote on its site.