Twitter and Facebook last month suspended hundreds of thousands of accounts and operations that they said were part of a Chinese state-linked disinformation campaign designed to discredit pro-democracy protests in Hong Kong.

A few days later, Google followed suit, banning 210 YouTube channels that it said it had identified as part of a similar disinformation effort.

Twitter published a list of the most active 936 accounts it banned and more than 3.6 million of their tweets, but it has not detailed how it ascertained that the accounts were connected to the Chinese state.

In its statement, Twitter highlighted behaviors that allowed it to trace many of these accounts to mainland China — a cause for suspicion given the ban on Twitter within the country. A Twitter spokesperson declined to elaborate on how these accounts were identified.

Twitter did say that the suspended accounts were all used at some point to promote China’s official narrative on Hong Kong’s protests, which casts the mass movement as a willfully destructive mob pushing for regime change in Hong Kong.

NPR’s data team and Beijing correspondent took a deep dive into the more than 900 accounts Twitter identified as linked to a Chinese state effort to discredit Hong Kong protesters. Here’s what we found.

China Used Twitter To Disrupt Hong Kong Protests, But Efforts Began Years Earlier

Graphics: Daniel Wood/NPR