China:
* The Great Firewall of China blocks people's access to many websites, e.g., Facebook, Google.
* Government engages in extensive censorship especially related to political organizing or protests.
* Foreign social media apps are banned. Users must use real names on social media.
The Great Firewall and the blocking of media apps does also function as a Firewall. It is not merely a censorship technology. The United States and allies are known to target media in other countries to stir dissent. Radio Free Europe, "Voice of Iraq" (cough American), the Lincoln Group infiltrations and partnerships, etc.
The Snowden leaks and the history of (especially) Google but also other US businesses in China (and export exceptions limiting the purchase of infrastructure technologies) tell a tale of the US trying to export compromised services to China. China does not want its citizens' informations in America's XKeyScore nor it's citizens Google, Microsoft, Apple, Facebook, etc data in America's PRISM. (There's a reason all of those programs get permission through the FISA "Foreign Intelligence Surveillance Act" Court).
Just this past year the CIA (under USAID) pretended to be a grassroots movement on Twitter served 'news' critical of the Cuban regime that nearly caused a Cuban uprising.
The DoD's MINERVA project specifically looks to understand the cultural components of stability of various countries and mechanisms to encourage or disrupt that stability. Among a great number of social studies you will find DoD research on how to seed information inside of specific Asian countries, including China, for the targeted introduction of instability. I will leave speculations of possible connections to the Hong Kong protests to the reader.
http://minerva.dtic.mil/funded.html
It's a global issue right now. This year Egypt sentenced Al Jazeera journalists that they believed were partnered with geopolitical interests of other states.
As of this year Putin is now requiring bloggers to register if they have a certain number of readers, so that his administration can curtail international influence.
America, too, faces challenges. A number of journalists have called out that the state has been extremely aggressive to dissenting opinions, even to go so far as labeling current policy on the issue "War on Journalism". American officials have exported a number of journalists with Middle Eastern descent and journalists like Ayman Mohyeldin have been pulled from Gaza and other conflicts when reporting has erred on the side of other state interests.
And of course there's the article "I Liked Everything I Saw on Facebook for Two Days", which is definitely worth a read. The TL;DR is that below the thin surface of social information bubbles enormous amounts of radicalizing geopolitical and domestic political ads and campaigns.
http://www.wired.com/2014/08/i-liked-everything-i-saw-on-fac...