In pre-modern times membership of a state was limited, allowing states to meet their obligations with relative ease. In the post-Westphalian system, where all those born into a state or being considered permanent residents of a state can claim membership of the polity, the demands placed on a state have grown exponentially. As globalisation has advanced not only have these demands grown but also they have become increasingly complex. The contemporary state can no longer address all the needs of all its peoples and societies through unilateral actions and programmes. It has little choice but to interact with other states, to help secure the necessary advantages and thus assure its legitimacy..