The gap between the demand for and the supply of global governance is greatest when it comes to the global commons, those spaces no nations control but on which we all rely for security and prosperity. The most important of these are the maritime, outer space, and cyberspace domains, which carry the flow of goods, data, capital, people, and ideas on which globalization rests. Ensuring free and unencumbered access to these realms is therefore a core interest not only of the United States but of most other nations as well.