How was the state defined as a major actor in international relations?

The state is considered a major actor in international relations due to its sovereignty, meaning it has the authority to govern within its borders without interference from external actors. States also have the ability to enter into international agreements, engage in diplomacy, and participate in international organizations, all of which contribute to their role as key players in the global arena. Additionally, states possess military capabilities and economic power that allow them to influence and shape the international system.