In summary, if the United States is to preserve the current favorable military balance in regions around the globe in the future, it will find itself increasingly dependent upon allies for support. This may require a somewhat different set of alliances than exists today. However, it will almost certainly require a very different division of labor. Restructuring alliance relationships to meet these requirements will take years, perhaps a decade or more, to accomplish. Yet the geopolitical and military revolutions that will likely stress US alliance relationships and key regional military balances are already well under way. Hence it is no exaggeration to say that a strategic assessment of America’s alliance relationships should be undertaken now, while the opportunity to shape the future is at its greatest.