Pacem, Dei Munus Pulcherrimum §17

¹⁷ Things being thus restored, the order required by justice and charity re-established and the nations reconciled, it is much to be desired, Venerable Brethren, that all States, putting aside mutual suspicion, should unite in one league, or rather a sort of family of peoples, calculated both to maintain their own independence and safeguard the order of human society. What specially, amongst other reasons, calls for such an association of nations, is the need generally recognized of making every effort to abolish or reduce the enormous burden of the military expenditure which States can no longer bear, in order to prevent these disastrous wars or at least to remove the danger of them as far as possible. So would each nation be assured not only of its independence but also of the integrity of its territory within its just frontiers.