The primary international political organization is the sovereign
state (since the Peace of Westphalia
Century was a period of radical expansion of independant states, but as different as each of these entities may be, they share many characteristics in common: sovereignty
, territory, population, armed forces, and the recognition
of other states. Under international law
the state is the only form of organization that has a legal right to use force
It is important to note that a state is not necessarily identifiable as a nation. In short, the former is a legal entity and the latter is a perceived entity (ethnic, language, etc.). The unfortunate confusion that arises is when people attempt to define all states as nation-states.
I admit double checking my terms and wording with Games Nations Play, 6th Ed. 1987.