This is the 42nd volume in the Occasional Paper series of the U.S. Air Force Institute for National Security Studies (INSS). This volume presents two important papers on United States military space. The first paper, "What is Spacepower and Does It Constitute a Revolution in Military Affairs?", examines the concept of "spacepower" as it is emerging within the U.S. military and business sectors to establish the basis for military space roles and implications. It also posits military-commercial sector linkages as the best near-term road map for future development. As commercial activities expand the importance of United States space, and as technological advances enable military missions, Hays sees expanded military roles, including space weaponization, on the horizon. He concludes that military space has already had a significant impact on the American way of war. That trend will only continue as the promise of a true space-led revolution in military affairs awaits eventual space weaponization. Given an increasingly important U.S. commercial and military presence in space, the second paper, "Space-Related Arms Control and Regulation to 2015: Precedents and Prospects," presents a detailed analysis of existing regulations and controls that constrain and shape military space use and development. It also presents a comprehensive examination of current and future issues that will define likely arenas of international efforts to further control military space. The United States must be very aware of the possible consequences for its overall commercial and military space efforts in addressing these issues. Finally, the paper suggests areas where some current regulatory emphasis could benefit the United States, indicating areas for current policy emphasis. Together, the two papers provide a timely and important examination of the current state and the likely future of United States military space.