Comparison: Defensive Realism vs Offensive Realism

Comparison: Defensive Realism vs. Offensive Realism

There are two main theories within the school of realism in international relations theory. These are defensive realism and offensive realism. These two fall under the greater theory of realism but each provides distinct assumptions that collectively explain the behaviors and actions of states relative to the supposed anarchy in the international system.

Similarities Between Defensive Realism and Offensive Realism

Realism is one of the main theories of international relations. Nevertheless, before discussing the differences between defensive realism and offensive realism, it is first important to underscore and understand their similarities and some of their shared assumptions.

Remember that both theories are derivatives of realism. One of their general assumptions is that states are the primary actors in the international system and there are no other greater actors that can effectively regulate their conduct. Even supranational organizations have no real authority over the behaviors and actions of these state actors.

Another similarity between defensive realism and offensive realism is that both assert that the international system is inherently anarchic because all state actors are primarily and perpetually driven to maintain power and promote internal security. The main drivers behind their behaviors and actions are their self-interest and the need to survive.

These two theories also assume that states can never be certain about the true intentions of other states while also asserting that states are still rational actors that are capable of developing and implementing strategies that maximize their prospect of survival.

Differences Between Defensive Realism and Offensive Realism

Defensive realism and offensive realism first emerged from the separate and contradicting works of two American political scientists. The former traces its roots back to the 1979 book “Theory of International Politics” by Kenneth Waltz and the latter finds its foundation in the 2001 book “The Tragedy of Great Power Politics” by John J. Mearsheimer.

The aforementioned works provided the groundwork used by adherents to expand and enrich further either of the two theories. There are now more materials or papers that have framed the theories within various contexts and phenomena. Nevertheless, considering these, below are the specific differences between defensive realism and offensive realism:

1. Core Arguments

Defensive realism asserts that states develop and implement policies and programs to promote security through a defensive approach. Offensive realism asserts that the programs and policies of states are aimed not only at promoting security but also at increasing their power to dominate the international system. Hence, based on this, one of the major differences between defensive realism and offensive realism centers on their different interpretations and diverging expansions of the general assumptions of realism.

2. Handling Anarchy

The international system is inherently anarchic according to realism. Defensive realism contends that states navigate through this anarchy by balancing their power through an arms race. A state that pursues dominance is counterbalanced by other states that seek to maintain the status quo. The international system punishes aggressors according to defensive realists. This is in contrast with offensive realism which asserts that states fundamentally desire dominance because they are actors that seek to maximize power with little regard for balancing. Hence, for offensive realists, the system rewards states that are able to achieve and maintain dominance.

3. Purpose of the Military

The primary purpose of the military of a particular state under defensive realism is to maintain security by building and improving the capacity for defending against aggressors. This defensive capacity is superior to offensive capacity. The collective military capabilities of different states also create a stabilizing effect. Offensive realism argues that the primary purpose of the military is to display the power of a particular state through aggression or to suppress other states through a demonstration of its military superiority.

4. State Survival

All states are driven by self-interest and self-preservation through power and security. Defensive realists and offensive realists both agree with this fact to a certain extent. Those who adhere to the principles of defensive realism believe that states are only interested in maintaining security through defensive measures and survival is attainable through a balance of power. Those who adhere to the principles of offensive realism assert that states are interested in conquests and that the best way to survive in the international system is to dominate and demonstrate their power while also preventing other states from attaining a similar level of power.

5. View on Mistrust

Another difference between defensive realism and offensive realism is the way each analyzes the concept of mistrust. Both claim that mistrust is pervasive because states can never be certain of the true and specific intentions of each other. Offensive realism contends that mistrust is not only prevalent in the international system but is also a constant. Defensive realism, however, opposes and argues that mistrust is amenable to change through international cooperation measures such as mutual security agreements.


  • Mearsheimer, J. J. 2001. The Tragedy of Great Power Politics. New York: W. W. Norton
  • Waltz, K. N. 1979. Theory of International Politics. New York: McGraw Hill