Weltbürgertum?

Cosmopolitanism? In 'Zum ewigen Frieden. Ein philosophischer Entwurf.' (1795), Immanuel Kant argues that true and worldwide peace is possible only when states organise themselves internally according to ‘republican’ principles, when they organise themselves externally in a voluntary league for the sake of keeping peace, and when they respect the human rights not only of their citizens but also of foreigners. Kant argues that the league of states should not have coercive military powers because that would violate the internal sovereignty of states. Is such a philosophy practicable, however?