In what has been dubbed “The Twitter Revolution,” citizens in Tehran since June have been documenting violence in the street and using social media to disseminate information to fellow protesters as well as an eager audience around the world. Their efforts bolster the idea that the Internet cannot be controlled, and that even the most repressive and determined government cannot stop the flow of information.

This is an appealing and exciting notion, one touted by many Iran watchers, but it ignores the fuller and more ominous reality of the cat and mouse game unfolding between journalists—professional and amateur—and those repressive regimes in Iran and elsewhere. Yes, Twitter and e-mail have made it possible to get fragmented bits of information out of Iran, but the hard-line government in Tehran may be winning the information war by forcing foreign correspondents out of the country or keeping them in their bureaus, shutting down reformist newspapers, rounding up critical bloggers and journalists, and, on occasion, disabling the Internet and cell service entirely. 

Beyond that, the situation in Iran points to serious vulnerabilities in the global information environment that have broad implications for journalism and press freedom: as more and more media outlets converge online, the Internet is becoming an information chokepoint that governments are seeking to control.

Pulling the plug on the Internet is an extreme measure, although Iran has done it for brief periods and China essentially shut down the Internet for months in Xinjiang province to prevent coverage of the unrest there. But governments from Tunisia to Vietnam are using monitors, filters, firewalls, and pressure on service providers to gain control of the Internet and stem the flow of information. In recent examples, government hackers have taken down critical Web sites in Russia and Tunisia. Governments are also jailing critical bloggers, who are vulnerable because, unlike professional journalists, they generally lack institutional backing.

In seeking to stem the flow of information online, governments have exploited vulnerabilities at each step in the journalism process: the gathering, dissemination, and consumption of news.

Before the Internet, news gatherers were mostly professional journalists. Over decades, governments around the world developed refined if imperfect strategies to control their activities, from denying visas and accreditation to the threat of prison sentences and even murder. But the Web changed the equation, since nearly everyone now has the capacity to gather and disseminate information using e-mail, the Web, social networking platforms, and, increasingly, SMS networks like Twitter. The sheer number of potential news gatherers presents new challenges to governments trying to stop information at its source. Iranian security forces, for instance, have made haphazard efforts to physically attack protesters who are using cell phones to document abuses. They are also attempting to use technology to suppress news gathering. According to media reports, Nokia Siemens, a Finnish-German joint venture, has sold Iran technology that allows authorities to monitor any communications across a network, including voice calls, text messaging, instant messages, and Web traffic. (The company says it provided only “Lawful Intercept capability solely for the monitoring of local voice calls in Iran.”) The Iranian government also set up a Web site asking people to help identify photos of protesters and turn them in.

If repressive governments cannot effectively control the information gatherers, they must either prevent them from disseminating the information or stop news consumers from accessing it. In both areas, governments have had surprising success. Their job is made easier by the fact that more and more information, whether collected by professional journalists or average citizens, is disseminated through the Web.

The simplest way to stop the dissemination of information or ideas is to limit access to the Internet or cellular networks. This is a strategy employed in some of the world’s most repressive countries, such as Burma and Cuba. By making it difficult for average citizens to get online, these governments inhibit the rise of mass citizen journalism, and make it easy to target the individuals who defy the government.

Burma, which was named the world’s worst place to be a blogger in a 2009 survey by the Committee to Protect Journalists (CPJ), broadly restricts Internet access, forcing people to access the Web through cyber cafés, which are carefully monitored. Bloggers caught disseminating damaging information have been severely punished. The comedian Muang Thura, for instance (better known as Zarganar, or “tweezers”), is serving a thirty-five-year sentence for distributing video of relief workers assisting the victims of Cyclone Nargis.

In Cuba, Internet access is officially restricted to government officials and members of the Communist Party, but a handful of independent bloggers operate in the country, using Internet cafés to access the Web. For the most part, Cuban authorities tolerate this because the bloggers don’t directly challenge the government and because their work is generally available only outside the island.

Joel Simon is a CJR columnist and the executive director of the Committee to Protect Journalists. His second book, The New Censorship: Inside the Global Battle for Media Freedom, was published by Columbia University Press in November 2014.