America is an aerospace nation. During the last 100 years, U.S. air and space competence has revolutionized the conduct of warfare, providing near-instantaneous global reconnaissance and the ability to precisely strike any target, anywhere, across the full spectrum of engagement, from combat operations to humanitarian aid. This competence has contributed to our ability to deter wars, as well as our ability to win them. However, in this new century, we find that rogue nations, the proliferation of weapons of mass destruction, and the rapid spread of information technology have the potential to threaten our national interests. This changing security environment presents us with both unique challenges and opportunities.