Conclusion

Abstract

The central argument in this volume has been that alliances are undergoing profound change due to the shift in the international distribution of power from bipolarity to unipolarity. This shift was particularly evident during the 1990s up to the mid-2000s, though it has been increasingly contested since. Despite persistent rumors of America’s imminent decline, however, the world remains unipolar for the time being. When all elements of national power are taken into consideration, the United States remains the world’s leading state. No competitor is yet capable of matching the United States in all areas simultaneously. In the form of national power that matters most to alliances — military power — US ascendancy is unquestioned. As Joseph Nye argues, the twenty-first century has begun with an unequal distribution of power, tilted in the favor of the United States; even as other powers particularly China catch up economically, the United States retains a mix of hard and soft power resources that remains unrivaled.¹ Unipolarity is uneven, however. The US lead is strongest in military terms, less so in economic terms. This gives the United States freedom to act to accomplish its military objectives with little assistance of allies, but leaves it vulnerable in the long term to inequitable burdensharing and free riding by allies.