The war between Israel and Iran, which overlaps with the war between Russia and Ukraine, makes the international scenario increasingly alarming. Let us leave aside the historical, political, and economic context in which these wars arose and developed and dwell on the moral problem on the horizon. In the Cold War era, the balance between the two superpowers, the United States and the Soviet Union, was ensured by the strategy of “deterrence,” or “mutual assured destruction” (MAD), according to which nuclear weapons, due to their destructive potential, constituted a tool to deter the enemy from an attack that would have a devastating response. Nuclear arsenals had as their sole purpose “to nullify nuclear weapons” (Herman Kahn, Philosophy of Atomic Warfare, tr. it., Il Borghese, Milan 1966, p. 138). In the post-modern era following the collapse of the Berlin Wall, there are no longer any shared international rules. The use of nuclear weapons is evoked, for example, by Vladimir Putin, as a means to rebalance military inferiority in the field of conventional weapons or, in the case of Iran, as a strategic goal to be achieved to destroy the State of Israel. One of the rules of deterrence was not to take the name of the bomb in vain. The verbal escalation we are witnessing could lead to actual war more quickly than we can imagine.
The basic question that now arises is this: would a nuclear response to a nuclear attack be lawful, or is a nuclear war itself inherently immoral, as Pope Francis held, who in Hiroshima on Nov. 24, 2019, declared, “The use of atomic energy for purposes of war is immoral, just as in the same way the possession of atomic weapons is immoral.” Is this the doctrine of the Church?
To resolve this complex moral problem, it must be remembered that over more than a millennium the Church has consistently taught the legitimacy of war waged for a just cause. This doctrine, after St. Augustine and St. Thomas, was further developed in its various aspects by the great Spanish theologians of the “Second Scholasticism,” such as the Dominican Francisco de Vitoria (1492-1546) and the Jesuit Francisco Suarez (1548-1617), and wasexpo unded by the great Catholic moralists and sociologists of the 20th century, such as Father Antonio Messineo (1897-1878) and Fr. Johannes Messner (1891-1894).
The modern era, however, has seen the birth and development of weapons such as atomic, biological, and chemical (A.B.C.) weapons, which differ from conventional ones not only in their degree of power but in their nature. They are, in fact, means of undifferentiated destruction, harming the innocent or the combatants themselves to an extent disproportionate to the results of war.
Pope Pius XII addressed this question in various speeches, but especially in his September 30, 1954 address to the Seventh World Medical Assembly, in which he asked, "Is modern ‘total war,’ A.B.C. war in particular, permitted in principle? There can be no doubt, especially because of the horrors and immense suffering caused by modern warfare, that to unleash it without just cause (i.e., without it being imposed by an obvious and extremely grave injustice, in no way avoidable) constitutes a crime worthy of the severest national and international sanctions. Similarly, the question of the permissibility of atomic, chemical, and bacteriological warfare cannot be raised as a matter of principle, except where it must be judged indispensable for defense under the conditions indicated. But even then all means must be attempted to avoid it, either by international understandings, or by placing very clear and strict limits on its use, so that its effects may remain limited to the strict requirements of defense. When, however, the use of this means involves such an extension of evil that it is entirely beyond human control, its use must be rejected as immoral. Here it would no longer be a matter of 'defense' against injustice and the necessary 'safeguarding' of legitimate possessions, but of the sheer annihilation of all human life within range. This is not permitted in any capacity" (Speeches and Radiomessages, vol. XVI, pp. 169).
The use of ABC warfare, we infer from Pius XII's passage, is permitted only if it is imposed by an extremely grave injustice, in no way avoidable, and if its effects can be controlled in some way.
Father Bernard de Lacoste Lareymondie, director of the Ecône Seminary of the Fraternity of St. Pius X in an article devoted in 2019 to this issue in “La Porte latine”, summarized the Catholic position well: "According to the fifth commandment of God, it is never licit to kill an innocent person directly. It is intrinsically evil. It is a mortal sin against justice. Therefore, even in the context of a just war, killing large numbers of civilians in order to drive the enemy to surrender is gravely immoral. If, however, it is a matter of indirectly killing an innocent person, the issue is more subtle. This is permissible under the following conditions: 1) That the death of the innocent person is not intended, but only expected, permitted and tolerated (St. Thomas Aquinas, Summa Theologica, II-II, 64, 6.); 2) That the death of the innocent person does not cause the desired good (Rom 3, 8); 3) That there is a proportionate cause (Summa Theologica, II-II, 64, 7)."
“It is this last condition,” Father Lareymondie continues, "that is in danger of not being met in the case of the atomic bomb. For example, if, while bombing an important enemy military base, I indirectly and unknowingly kill two or three civilians, proportionate cause is present. But if, in order to kill five enemy soldiers, I run the risk of causing the death of hundreds of civilians, proportionate cause is not present. However, the atomic bomb is extremely devastating. Its use will be legitimate only if the damage caused to civilians is very limited. That is why it is very difficult to justify the bombing of Hiroshima and Nagasaki in August 1945."
"But does this mean that the atomic bomb itself is immoral? Certainly not. The morality of a weapon derives not from its nature but from the use men make of it. (...) The difficulty lies in the destructive effects of this bomb: they are terrible and difficult to control. However, it is not impossible to imagine a situation in which innocent victims of nuclear weapons would be few. These are cases in which the enemy military target is distinctly isolated. For example, if a powerful enemy military base is located in the middle of a desert, or on a sparsely populated island in the Pacific Ocean, then, if the war is just, the use of an atomic bomb might be morally permissible, provided that the power of the bomb is proportionate, as far as possible, to the size of the target. This bomb could also be legitimately dropped on a squadron at sea far from the coast. It must be recognized, however, that such a situation is not frequent, and that consequently, more often than not, the use of the atomic bomb is not justified, because of the disproportion between the death of so many innocents and the desired military result."
The conclusions, quite different from Pope Francis' position, are clear: "Military nuclear energy is not in itself immoral. It is true, however, that the conditions for it to be right are such that, in practice, the use of the atomic bomb would very rarely be morally permissible. But this conclusion is sufficient to make the possession of nuclear weapons permissible."
To sum up: for a war to be just, it is necessary for not only the end but also the means used to fight it to be good and just. In a nuclear war, it may be good for the end, for example in the case of aggression suffered, but it is unlikely to be good for the means, if this involves the death of tens of thousands of innocent civilians, affected as a direct target. Traditional morality does not admit the Machiavellian maxim that the end justifies the means. No evil done with good intention can be excused, “as those who say, Let us do evil that good may come; the condemnation of whom is just” (Rom. 3:8).
