Beijing has recently added a new weapon to its arsenal of surveillance technologies, a system it believes to be a modern marvel: the Golden Shield. It took eight years and $700 million to build, and its mission is to “purify” the Internet — an apparently urgent task. “Whether we can cope with the Internet is a matter that affects the development of socialist culture, the security of information, and the stability of the state,” President Hu Jintao said in January.

The Golden Shield — the latest addition to what is widely referred to as the Great Firewall of China — was supposed to monitor, filter, and block sensitive online content. But only a year after completion, it already looks doomed to fail. True, surveillance remains widespread, and outspoken dissidents are punished harshly. But my experience as a correspondent in China for seven years suggests that the country’s stranglehold on the communications of its citizens is slipping: Bloggers and other Web sources are rapidly supplanting Communist-controlled news outlets. Cyberprotests have managed to bring about an important constitutional change. And ordinary Chinese citizens can circumvent the Great Firewall and evade other forms of police observation with surprising ease. If they know how.

Like its namesake, the Great Firewall consists of hundreds of individual fortifications spread out along a vulnerable frontier. At its core is a giant bank of computers and servers. Traffic generated by China’s 162 million Internet users is routed through the shield, which checks all requested URLs against a blacklist of tens of thousands of Internet addresses. The list includes pages offering political information deemed dangerous by the government, like BBC News and Voice of America. Access to these sites is blocked (at least in theory), and when users attempt to view one of them, they are punished with an involuntary time-out lasting anywhere from 30 seconds to 30 minutes. Search engines are similarly restricted. If you enter the characters for “democracy” or “Tiananmen Square massacre” into you will generally get zero results. This is a technological breakthrough for the Chinese government. Until recently, it could not interfere with the inner workings of search engines and instead blocked entire sites, not just individual pages of a site.

The Golden Shield hardware — supplied by Cisco and other US companies — is supplemented by human censors who are paid about $170 a month. They sit at screens in warehouse-like buildings run by the Public Security Bureau. These foot soldiers in China’s information war monitor domestic news sites, erasing and editing politically sensitive stories. Some sites provide the censors with access so the authorities can alter content directly. Others get an email or a call when changes are required. Similar methods are applied to blogs. Sensitive entries are erased, and in the most egregious cases blogs are shut down altogether.