China’s censorship of the Internet and its tight control over traffic in and out of the country are well known. Internet protocol version 6 has the potential to give China an even tighter grip. Because each Internet-connected device has a unique IP address, it could be easier for the government to track users who post pro-democracy messages online or who try to use the Web to organize protests. Members of the international IPv6 community say that every IPv6-enabled device will come with two addresses that a user can flip between: an authenticated one for transactions and an anonymous one for Web browsing and other activities. But because next-generation Internet service is not commercially available in China yet, it remains to be seen what the real-world implementation will look like.

China’s NextGeneration Internet (CNGI) has U.S. national security implications as well. While the level of Chinese military involvement in CNGI is unclear, the People’s Liberation Army has designed its own IPv6 router, and a recent China IP Council white paper mentions that IPv6 networks have “military and intelligence” uses. Unrestricted Warfare, a widely translated treatise on military doctrine written by two People’s Liberation Army officers, calls for China to engage the West in nontraditional combat, and suggests tactics such as computer hacking and cyberterrorism.

Meanwhile, if China moves to an IPv6 network while the United States is still running IPv4, Internet traffic coming from China will be impossible to track back to its source, says James Mulvenon, deputy director of the Center for Intelligence Research and Analysis, which advises the U.S. intelligence community. “Imagine if you are running an army network at Fort Hood and you detect hostile packets,” he says. If the packets are coming from or through China, “you can’t tell anything about them. It turns China into a big anonymizer.”