113 Everyone, however, must realize that, unless this process of disarmament be thoroughgoing and complete, and reach men's very souls, it is impossible to stop the arms race, or to reduce armaments, or—and this is the main thing—ultimately to abolish them entirely. Everyone must sincerely co-operate in the effort to banish fear and the anxious expectation of war from men's minds. But this requires that the fundamental principles upon which peace is based in today's world be replaced by an altogether different one, namely, the realization that true and lasting peace among nations cannot consist in the possession of an equal supply of armaments but only in mutual trust. And We are confident that this can be achieved, for it is a thing which not only is dictated by common sense, but is in itself most desirable and most fruitful of good.
Source: Pacem in Terris (Vatican.va)