Cybersecurity is a growing concern for most governments. While the United States probably has tighter defenses than China, for example, experts say it relies more heavily on computers to run its infrastructure and so is more vulnerable to an attack.

But for China, worries about how foreign forces might employ the Internet and other communications advances to unseat the Communist Party are a salient factor in the government’s 15-year effort to control those technologies. Chinese leaders are constantly trying to balance the economic and social benefits of online freedoms and open communications against the desire to preserve social stability and prevent organized political opposition.

A distinct shift in favor of more comprehensive controls began nearly two years ago and hardened over the past six months, analysts say.

New policies are intended to replace foreign hardware and software with homegrown systems that can be more easily controlled and protected. Officials are also expanding the reach and resources of state-controlled media outlets so they dominate Chinese cyberspace with their blogs, videos and news. At the same time, the government is beefing up its security apparatus. Officials have justified stronger measures by citing various internal threats that they say escalated online. Among them: the March 2008 riots in the Tibetan capital, Lhasa; reported attempts to disrupt the August 2008 Olympic Games and the amassing of more than 10,000 signatures supporting a petition for human rights and democratic freedoms, an example of how democracy advocates could organize online.

Especially alarming to officials, analysts say, was the role of the Internet in ethnic riots last July that left nearly 200 people dead and more than 1,700 injured  the worst ethnic violence in recent Chinese history. Government reports asserted that terrorists, separatists and religious extremists from within and outside the country used the Internet to recruit Uighur youth to travel to Urumqi, the capital of western China’s Xinjiang region, to attack ethnic Han citizens.

Image An Internet cafe in Beijing. Credit... Shiho Fukada for The New York Times

In August, security and propaganda officials briefed China’s ruling Politburo on their view of how the Xinjiang riots developed, according to one media executive with high-level government ties. The executive spoke on the condition of anonymity for fear of retribution for discussing delicate political topics.