unipole and other states, and exclusively among other states. Monteiro substantiates this by remarking that “the United States has been at war for thirteen of the twenty-two years since the end of the Cold War. Put another way, the first two decades of unipolarity, which make up less than 10 percent of U.S. history, account for more than 25 percent of the nation’s total time at war.” Kenneth Waltz that unipolarity is “the least durable of international configurations.” Secondly, even if the United States acts benevolently, states will still attempt to balance against it because the power asymmetry demands it: In a self-help system, states do not worry about other states’ intentions as they do other states' capabilities. “Unbalanced power leaves weaker states feeling uneasy and gives them reason to strengthen their positions,” Waltz says. In a 2009 study, Martha Finnemore argues that unipolarity has, contrary to some expectations, not given the United States a free rein to do what it wants and that unipolarity has proven to be quite frustrating for the United States. The reasons for this is that unipolarity does not just entail a material superiority by the unipole, but also a social structure whereby the unipole maintains its status through legitimation, and institutionalization. In trying to obtain legitimacy from the other actors in the international system, the unipole necessarily gives those actors a degree of power. The unipole also obtains legitimacy and wards off challenges to its power through the creation of institutions, but these institutions also entail a diffusion of power away from the unipole. In a 2021 study, Yuan-kang Wang argues from the experience of Ming China (1368–1644) and Qing China (1644–1912) that the durability of unipolarity is contingent on the ability of the unipole to sustain its power advantage and for potential challengers to increase their power without provoking a military reaction from the unipole. American primacy Numerous thinkers predicted U.S primacy in the 20th century onwards, including William Gladstone, Michel Chevalier, K'ang Yu-wei, Georges Vacher de Lapouge, H. G. Wells in Anticipations (1900), and William Thomas Stead. Liberal institutionalist John Ikenberry argues in a series of influential writings that the United States purposely set up an international order after the end of World War that sustained US primacy. In his view, realist predictions of power balancing did not bear fruit because the United States engaged in strategic restraint after World War II,