While the Internet is emerging as an increasingly powerful tool for political activism—most recently demonstrated in the Middle East up-risings—so governments around the world are becoming more expert in the means and methods to control electronic communication. This is the conclusion reached by a new report by the respected human-rights organization Freedom House, “Freedom on the Net 2011: A Global Assessment of Internet and Digital Media.”

The report complements Freedom House’s long standing annual “Freedom in the World” report, adding a new dimension to its treatment of freedom of expression. “Freedom on the Net,” however, does not cover the entire world but a selection of 37 countries, among them the world’s most egregious abusers.

Over 2 billion people worldwide have some degree of access to the Internet, a figure that has doubled over the past five years. In tandem with that growth, Web site blocking, filtering, manipulation, and cyber attacks by governments that feel threatened by this new communications tool have all increased massively as well. Of the 37 countries examined, 15 engaged in substantial blocking of politically relevant material. As the report notes, this blocking was deliberate, systematic, and comprehensive, covering thousands of Web sites, news outlets, and human rights groups.

Some of the worst offenders on the list will hardly surprise anyone—Bahrain, Belarus, China, Cuba, Ethiopia, Iran, Kazakhstan, Pakistan, Saudi Arabia, Thailand, Tunisia, and Vietnam. Yet two electoral democracies have also landed on this list: Turkey (for its practice of blocking YouTube) and South Korea (for blocking North Korean Web sites). North Korea, arguably the most repressive regime on earth, is absent from the discussion, possibly offering little data for analysis, which depends on local activists and Internet users volunteering to register their conclusions with Freedom House about Web use in their countries.

Cyber aggression is also on the rise. The number of technical attacks on activists’ online networks is growing in at least 12 of the countries recorded in the report. China is a major global source of cyber attacks, and though not all of them can be traced back to the government, the sheer scale and organization suggest that they are at the very least sponsored or endorsed by the government. Interestingly, the Freedom House report comes at a time when the U.S. government is considering ending all its broadcasting to China by Voice of America and relying solely on its Chinese language Web site for news to China. Guess how much controversial news reporting the Chinese government will allow to get through.

The United States, thankfully, is close to the top of the list of countries with Internet freedom, second only to Estonia. Still, it is clear that the Internet today as a medium remains highly vulnerable and easily compromised. Control of the cyber battle space will be a key freedom issue in the future, but at least Freedom House has given policymakers a tool to measure the magnitude of the challenge at hand.