The Internet is often described as a miracle of self-regulation, which is almost true. The exception is that the United States government has had ultimate control from the beginning. Washington has used this oversight only to ensure that the Internet runs efficiently and openly, without political pressure from any country.

This was the happy state of affairs until last Friday, when the Obama administration made the surprise announcement it will relinquish its oversight of the Internet Corporation for Assigned Names and Numbers, or Icann, which assigns and maintains domain names and Web addresses for the Internet. Russia, China and other authoritarian governments have already been working to redesign the Internet more to their liking, and now they will no doubt leap to fill the power vacuum caused by America's unilateral retreat.

Why would the U.S. put the open Internet at risk by ceding control over Icann? Administration officials deny that the move is a sop to critics of the National Security Agency's global surveillance. But many foreign leaders have invoked the Edward Snowden leaks as reason to remove U.S. control—even though surveillance is an entirely separate topic from Internet governance.

According to the administration's announcement, the Commerce Department will not renew its agreement with Icann, which dates to 1998. This means, effective next year, the U.S. will no longer oversee the "root zone file," which contains all names and addresses for websites world-wide. If authoritarian regimes in Russia, China and elsewhere get their way, domains could be banned and new ones not approved for meddlesome groups such as Ukrainian-independence organizations or Tibetan human-rights activists.

Until late last week, other countries knew that Washington would use its control over Icann to block any such censorship. The U.S. has protected engineers and other nongovernment stakeholders so that they can operate an open Internet. Authoritarian regimes from Moscow to Damascus have cut off their own citizens' Internet access, but the regimes have been unable to undermine general access to the Internet, where no one needs any government's permission to launch a website. The Obama administration has now endangered that hallmark of Internet freedom.