The Unipolar World explains the international politics of the contemporary world.  It completes structural realism by setting forth a theory of international politics when there is only one superpower. The authors distinguish between unipolarity and hegemony, and make analogy to the price leader model of microeconomics.  Their research support realist predictions that a unipolar world will be relatively stable, and characterized by bandwagoning, flexible alliances, and resistance by the unipolar power to international law.  When defensive power seems to have an advantage, the unipolar power will avoid involvement in international conflict, and unipolarity will be reinforced  When offensive poser seems to have an advantage, the unipolar power will launch preventive wars, undermining its position in the international system.