According to neorealism, what is the primary driver of state behavior in the international system?

According to neorealism, also known as structural realism, the primary driver of state behavior in the international system is the structure of the international system itself, specifically the distribution of power among states. Unlike classical realism, which attributes state behavior to inherent human nature or domestic politics, neorealism emphasizes that the anarchic nature of the international system forces states to prioritize their own survival and security. Anarchy, in this context, means the absence of a central authority or world government above states. Because there is no higher power to protect them, states must rely on their own capabilities to ensure their security. The distribution of power, or how power is spread among states, shapes the interactions and behaviors of states within this anarchic system. When power is concentrated in a few states (a condition known as polarity, either unipolarity, bipolarity, or multipolarity), it affects the stability and dynamics of the system. For example, during the Cold War, the international system was bipolar, meaning power was largely concentrated between the United States and the Soviet Union, which heavily influenced alliance formation and security strategies as states aligned with or balanced against these major powers. States are primarily concerned with their relative power position in the system. This means they are less concerned with absolute gains (gaining wealth or resources in general) and more concerned with how their gains compare to the gains of other states. They want to ensure that they do not fall behind or become vulnerable to other states. Therefore, states constantly monitor each other's capabilities and intentions, engaging in a self-help system where they must continuously seek ways to enhance their own security, often through military build-up, forming alliances, or adopting balancing strategies to prevent any single state from becoming too dominant. The structure of the system compels states to behave in certain ways, regardless of their individual preferences or ideologies. The system's structure, defined by anarchy and the distribution of power, is thus the overriding factor influencing state behavior, pushing them to prioritize survival and security in a competitive environment.