While China uses the centuries-old weapons of prisons and punishment to control its own writers and thinkers, it plies much more sophisticated tools in handling the foreign media.
"China has the technology to intercept everything from telephone calls to electronic mail, and we assume it uses that know-how to monitor some journalists and diplomats," says a Western official in Beijing.
While foreign reporters may face brief detention or expulsion from China for interviewing political or human rights activists, Chinese sources face a far more devastating array of penalties.
After former student protest leader Wang Dan was freed from his first jail term in 1993, he said that police questioned him regularly about contacts with foreign reporters. Selected passages from Mr. Wang's quotes in the overseas media were cited as evidence of subversion during his second trial in 1996.
Four of the 10 imprisoned writers whose names appear on an amnesty appeal issued by the Committee to Protect Journalists are serving time for leaking ill-defined "state secrets" to foreign reporters, says press rights activist Lin Neumann.
"One editor received a life sentence for leaking a copy of a speech by [President] Jiang Zemin" in 1992, he says.
Just last month, the authorities here sentenced Yang Qinheng to three years at a labor camp for calling a talk show show sponsored by the US-based Radio Free Asia and appealing for free trade unions in China.
Radio Free Asia chief Dick Richter says Yang "was accused of inciting counterrevolutionary protests" and sent to the labor camp without a trial. "We see this as a warning not only to people like Yang, but also to Radio Free Asia," he adds.
The Chinese government often labels the radio station a relic of the cold war, and sporadically attempts to jam its broadcasts.
Mr. Richter also rejects the accusation that Radio Free Asia aims to harm China's image in order to contain it - a charge that is also leveled against many American newspapers and magazines that have offices in Beijing. "Our mandate is to be a surrogate for the media that are repressed inside of China," he says.