China shut down cell phone and Internet service in Urumqi, a city in western China, as soon as riots broke out between the (Moslem and Turkic) Uighur majority there, and the Han (ethnic Chinese) minority. Last year, when similar riots broke out in Tibet, it took ten days before the government took similar measures. In addition, the government ordered their Golden Shield (Internet monitoring and censoring) operation to keep pro-Uighur material off the Chinese Internet. This is done using the existing filtering tools, which block message board or blog postings that contain forbidden words or phrases. In addition, some of the 30,000 Golden Shield staffers personally monitor message boards and chat rooms that are suspected of generating politically incorrect discussion of events. Internet users who say the wrong thing too often are arrested, or ordered to report to a police station for an interview. Some of the more troublesome bloggers or posters go to jail.
All this is the result of years of effort. It all began in the late 1990s, when the Chinese Defense Ministry established the "NET Force." This was initially a research organization, which was to measure China's vulnerability to attacks via the Internet. Soon this led to examining the vulnerability of other countries, especially the United States, Japan and South Korea (all nations that were heavy Internet users). NET Force has continued to grow ever since.
NET Force was soon joined by an irregular civilian militia; the "Red Hackers Union" (RHU). These are several hundred thousand patriotic Chinese programmers and Internet engineers who wished to assist the motherland, and put the hurt, via the Internet, on those who threaten or insult China. The RHU began spontaneously, but the government has assumed some control, without turning the voluntary organization into another bureaucracy. Various ministries have liaison officers who basically keep in touch with what the RHU is up to (mostly the usual geek chatter), and intervene only to "suggest" that certain key RHU members back off from certain subjects or activities. Such "suggestions" carry great weight in China, where people who misbehave on the web are very publicly prosecuted and sent to jail. For those RHU opinion-leaders and ace hackers that cooperate, there are all manner of benefits for their careers, not to mention some leniency if they get into some trouble with the authorities. Many government officials fear the RHU, believing that it could easily turn into a "counter-revolutionary force." So far, the Defense Ministry and NET Force officials have assured the senior politicians that they have the RHU under control.
Around the same time, China began building what has now become 30,000 Ministry of Public Security employees manning the Golden Shield Project (also known as The Great Firewall of China), and monitoring Internet use throughout the country. In the last decade, over a billion dollars has been spent on this effort. While the Great Firewall cannot stop someone expert at how the Internet works, it does greatly restrict the other 99 percent of Internet users. And it provides lots of information about what is going on inside all that Internet traffic.
Year by year, the Golden Shield operators learned what worked (to control news) and what didn't. Not only can Golden Shield keep news from getting out of a part of China, but it can greatly limit how much contradictory (to the government version) news gets into all of China. The effective crackdown on news about rioting Uighurs was not a fluke, but the result of over a decade of experience and effort.