How do defensive realists and offensive realists disagree about state behavior?

Defensive and offensive realism are two branches of neorealism that disagree on how the anarchic international system shapes state behavior. Both schools agree that the absence of a central authority forces states to prioritize survival and rely on self-help, but they differ on the primary objective states pursue to achieve that security.12

Defensive Realism

Following the work of Kenneth Waltz, defensive realists argue that states are primarily security maximizers. Because aggressive expansion often triggers balancing behavior from other states—leading to a security dilemma—defensive realists contend that it is rational for states to maintain the status quo. In this view, a stable international equilibrium is possible through balancing, and states generally avoid excessive power accumulation to prevent provoking their rivals.213

Offensive Realism

In contrast, offensive realists, most notably John J. Mearsheimer, argue that the anarchic system provides strong incentives for states to be aggressive power maximizers. They contend that because states can never be certain of others' intentions, the most rational way to ensure survival is to diminish the power of competitors and enhance one's own. Consequently, offensive realists believe that states constantly seek to maximize their relative power, making a stable equilibrium much harder to achieve than defensive realists suggest.21