The balance of power is one of the oldest and most fundamental concepts in international relations theory. Although there are many variations of balance of power theory and interpretations of the concept, all are premised on the minimum of a tendency and the maximum of a lawlike recurrent equilibrium model. According to this model, imbalances and concentrations in military and material capabilities among the great powers are checked, and the equilibrium is restored in order to ensure the survival of the major powers in the international system. The great powers have several mechanisms to restore the balance, including internal military buildup where economic wealth is converted into military power, the formation of counterbalancing alliances, passing the buck of balancing to another state, partition and compensation in postwar peace settlements, and emulation. In contrast, many scholars find that secondary and tertiary states are more likely to bandwagon or join with the more powerful state or coalition of states rather than balance against it. Based on structural realism as advanced by Kenneth Waltz in Theory of International Politics (New York: Random House, 1979), the self-help anarchic system and shifts in the relative distribution of capabilities mean that balances of power recurrently form in the international system. How states balance will depend on the distribution of capabilities among the greater powers. In bipolar distributions of power (two great powers) states will balance through internal military buildup. In multipolar distributions of power (three or more) states will balance through the formation of counterbalancing alliances. Finally, according to John Mearsheimer, in balanced multipolar distributions of power (three or more equally powerful states), great powers are likely to pass the buck of balancing or “buck pass” to a “buck catcher” the responsibility of balancing. In the current unipolar distribution of power, a number of scholars contend that states are engaging in soft balancing and leash slipping rather than traditional hard balancing. Others contend that no balancing is occurring and the imbalanced or unipolar distribution is both durable and stable.