US Internet governance policy, it has been argued, is a threat to the Internet. Calls persist for the development of a multilateral Internet governance organization where states, especially the United States, play a lessened Internet governance role. Yet, US policymakers continue to resist greater multilateralism in global Internet governance favoring instead multistakeholder governance. Why do US policymakers continue to resist greater multilateralism in global governance of the Internet? Employing the Open Door interpretation of US diplomatic history, I show that, in the post–Cold War era, US policymakers purposed the Internet as a platform for the expansion of American products and political ideals and view greater multilateralism in global Internet governance as a threat to this purpose for the Internet. US policymakers will continue to support the present multistakeholder Internet governance structure that reflects US Internet governance policy preferences. Efforts at greater multilateralism in global governance of the Internet will continue to encounter US resistance unless such efforts incorporate US Internet governance policy preferences.