International organizations for example the UN, treaties, and economic globalization, have all begun to subtly constrain the states' freedom of action, and therefore has eroded their jurisdiction from above. It must be pointed out here that jurisdictional boundaries make neither borders nor sovereignty. All polities are subdivided into smaller units for administrative purposes to some extent. These subdivisions imply jurisdictions with discrete boundaries. In federal systems, the subdivisions have some degree of autonomy themselves, in the sense that they have discretion in certain areas and cannot be over-ridden by the centre. Yet federal units are considered part of the federation and not separate sovereignties. Ever since the founding of the UN there have been restrictions on states' sovereignty from above, on their right to engage in aggression against their neighbours for example. In the course of time, countries have signed up to more and more treaties which prevent them from, say, testing nuclear weapons, or abusing the rights of children. The UN and international treaties are notoriously weak, but they still create a conceptual puzzle: what is the difference between a "sovereign" polity which abrogates certain rights by international treaty and a federal unit which abrogates certain rights in favour of a federal government. This question is as old as the United Nations, as the name of the United Nations suggests; the UN embodies an aspiration towards some sort of world federation.