A sustainable national security strategy is feasible only when directed by a sustainable national security policy. In the absence of policy guidance, strategy will be meaningless. The only policy that meets both the mandates of American culture and the challenges of the outside world is one that seeks to lead the necessary mission of guarding and advancing world order. The author considers and rejects a policy that would encourage the emergence of a multipolar structure to global politics. He argues that multipolarity not only would fail to maintain order, it would also promote conflict among the inevitably rival great powers. In addition, he suggests Americans culturally are not comfortable with balance-of-power politics and certainly would not choose to promote the return of such a system. Various “pieces of the puzzle” most relevant to national security strategy are located; leading assumptions held by American policymakers and strategists are identified; alternative national security policies are considered; and necessary components of a sustainable national security strategy are specified. The author concludes that America has much less choice over its policy and strategy than the public debate suggests. He warns that the country’s dominant leadership role for global security certainly will be challenged before the century is old.