Pope John XXIII
Pacem in Terris §128
Pacem in Terris: On Establishing Universal Peace in Truth, Justice, Charity, and Liberty
128 And yet, unhappily, we often find the law of fear reigning supreme among nations and causing them to spend enormous sums on armaments. Their object is not aggression, so they say—and there is no reason for disbelieving them—but to deter others from aggression.
Source: Pacem in Terris (Vatican.va)