WASHINGTON - Hours before the judge in the latest Mikhail Khodorkovsky trial announced yet another guilty verdict last week, Russia's most prominent political prisoner was already being attacked in cyberspace.

No, Khodorkovsky's Web site, the main source of news about the trial for many Russians, was not being censored. Rather, it had been targeted by so-called denial-of-service attacks, with most of the site's visitors receiving a "page cannot be found" message in their browsers.

Such attacks are an increasingly popular tool for punishing one's opponents, as evidenced by the recent online campaign against American corporations like Amazon and PayPal for mistreating WikiLeaks. It's nearly impossible to trace the perpetrators; many denial-of-service attacks go underreported, as it's often hard to distinguish them from cases where a Web site has been overwhelmed by a huge number of hits. Although most of the sites eventually get back online, denial-of-service attacks rarely generate as much outrage as formal government attempts to filter information on the Internet.

In the past, repressive regimes have relied on Internet firewalls to block dissidents from spreading forbidden ideas; China has been particularly creative, while countries like Tunisia and Saudi Arabia are never far behind. But the pro-Kremlin cyberattackers who hit Kodorkovsky's Web site may reveal more about the future of Internet control than Beijing's practice of adapting traditional censorship to new technology.

Under the Russian model - what I refer to as "social control" - no formal, direct censorship is necessary. Armies of pro-government netizens - which often include freelancing amateurs and computer-savvy members of pro-Kremlin youth movements - take matters into their own hands and attack Web sites they don't like, making them inaccessible even to users in countries that practice no Internet censorship at all.

Cyberattacks are just one of the growing number of ways in which the Kremlin harnesses its supporters to influence Web content. Most of the country's prime Internet resources are owned by Kremlin-friendly oligarchs and government-controlled companies. These sites rarely hesitate to suspend users or delete blog posts if they cross the line set by the government.

The Kremlin is also aggressively exploiting the Internet to spread propaganda and bolster government popularity, sometimes with comical zeal. Just last summer Vladimir Putin ordered the installation of Web cameras - broadcasting over the Internet in real-time - to monitor progress on new housing projects for victims of the devastating forest fires. This made for great PR - but few journalists inquired whether the victims had computers to witness this noble exercise in transparency (they didn't). Russia's security services and police also profit from digital surveillance, using social networking sites to gather intelligence and gauge the popular mood.

The Kremlin in fact practices very little formal Internet censorship, preferring social control to technological constraints. There is a certain logic to this. Outright censorship hurts its image abroad: Cyberattacks are too ambiguous to make it into most foreign journalists' reports about Russia's worsening media climate. By allowing Kremlin-friendly companies and vigilantes to police the digital commons, the government doesn't have to fret over every critical blog post.

One reason so many foreign observers overlook the Kremlin's harnessing of denial-of-service attacks is that they are used to more blatant measures of Internet control. China's draconian efforts to filter the Internet - characterized by Wired magazine in a 1997 article as the "Great Firewall of China" - harken back to the strict censorship of the airways by Communist governments during the Cold War. Back then it was possible to keep out or at least cut down on the influence of foreign ideas by jamming Western broadcasts. The Internet, however, has proven to be far too amorphous to dominate. So its better to co-opt it as much as possible by enabling private companies and pro-government bloggers to engage in "comment warfare" with the Politburo's foes.

Meanwhile, China itself is quietly adopting many measures practiced in Russia. The Web site of the Norwegian Nobel Committee came under repeated cyberattacks after it gave the 2010 award to the jailed Chinese dissident Liu Xiaobo. Many Chinese government officials are now asked to attend media training sessions and use their skills to help shape online public opinion rather than censor it.

In assessing the U.S. government's Internet freedom policy - announced a year ago by Hillary Clinton - one sees few signs that U.S. diplomats are aware of growing efforts by authoritarian governments to harness social forces to control the Internet. So far, most of Washington's efforts have been aimed at limiting the damage caused by technological control. But even here Washington has a spotty record: Just a few weeks ago the State Department gave an innovation award to Cisco, a company that played a key role in helping China build its firewall.

The eventual disappearance of Internet filtering in much of the world would count as a rather ambiguous achievement if it's replaced by an outburst of cyberattacks, an increase in the state's surveillance power, and an outpouring of insidious government propaganda. Policymakers need to stop viewing Internet control as just an outgrowth of the Cold War-era radio jamming and start paying attention to non-technological threats to online freedom.

Addressing the social dimension of Internet control would require political rather than technological solutions, but this is no good reason to cling to the outdated metaphor of the "Great Firewall."

Evgeny Morozov is a visiting scholar at Stanford University and the author of "The Net Delusion: The Dark Side of Internet Freedom."