I was teaching at the time and the head of the board had lunch with me and asked me to explain my position, as the entire faculty, but me supported the war. I explained, as I had in religion classes, that the Church did no support strikes which may stop a war as part of the Just War doctrine. Preemptive strikes are not part of the criteria for a just war.
The Catholic Church has been clear on the doctrine of Just War. Defense and means, as well as reason for such must follow real criteria. Sadly, too many Catholics have not understood the Church's position and either fall into false pacifism or false aggression. Here are some of the points Note, a summary of the CCC as to the necessary criteria for a Just War may be seen in a previous post.
Therefore, there are times when a Catholic can object to national aggression. Not all wars are just. One may be against a particular war and still uphold the Just War doctrine.
Here is another source
http://www.vatican.va/roman_curia/pontifical_councils/justpeace/documents/rc_pc_justpeace_doc_20060526_compendio-dott-soc_en.html
III. THE FAILURE OF PEACE: WAR
497. The Magisterium condemns "the savagery of war" [1032] and asks that war be considered in a new way.[1033] In fact, "it is hardly possible to imagine that in an atomic era, war could be used as an instrument of justice".[1034] War is a "scourge" [1035] and is never an appropriate way to resolve problems that arise between nations, "it has never been and it will never be",[1036] because it creates new and still more complicated conflicts.[1037] When it erupts, war becomes an "unnecessary massacre",[1038] an "adventure without return"[1039] that compromises humanity's present and threatens its future. "Nothing is lost by peace; everything may be lost by war".[1040] The damage caused by an armed conflict is not only material but also moral.[1041] In the end, war is "the failure of all true humanism",[1042] "it is always a defeat for humanity": [1043] "never again some peoples against others, never again! ... no more war, no more war!" [1044]
498. Seeking alternative solutions to war for resolving international conflicts has taken on tremendous urgency today, since "the terrifying power of the means of destruction - to which even medium and small-sized countries have access - and the ever closer links between the peoples of the whole world make it very difficult or practically impossible to limit the consequences of a conflict".[1045] It is therefore essential to seek out the causes underlying bellicose conflicts, especially those connected with structural situations of injustice, poverty and exploitation, which require intervention so that they may be removed. "For this reason, another name for peace is development. Just as there is a collective responsibility for avoiding war, so too there is a collective responsibility for promoting development".[1046]
499. States do not always possess adequate means to provide effectively for their own defence, from this derives the need and importance of international and regional organizations, which should be in a position to work together to resolve conflicts and promote peace, re-establishing relationships of mutual trust that make recourse to war unthinkable.[1047] "There is reason to hope ... that by meeting and negotiating, men may come to discover better the bonds that unite them together, deriving from the human nature which they have in common; and that they may also come to discover that one of the most profound requirements of their common nature is this: that between them and their respective peoples it is not fear which should reign but love, a love which tends to express itself in a collaboration that is loyal, manifold in form and productive of many benefits".[1048]
a. Legitimate defence
500. A war of aggression is intrinsically immoral. In the tragic case where such a war breaks out, leaders of the State that has been attacked have the right and the duty to organize a defence even using the force of arms.[1049] To be licit, the use of force must correspond to certain strict conditions: "the damage inflicted by the aggressor on the nation or community of nations must be lasting, grave and certain; all other means of putting an end to it must have been shown to be impractical or ineffective; there must be serious prospects of success; the use of arms must not produce evils and disorders graver than the evil to be eliminated. The power of modern means of destruction weighs very heavily in evaluating this condition. These are the traditional elements enumerated in what is called the 'just war' doctrine. The evaluation of these conditions for moral legitimacy belongs to the prudential judgment of those who have responsibility for the common good".[1050 ]
If this responsibility justifies the possession of sufficient means to exercise this right to defence, States still have the obligation to do everything possible "to ensure that the conditions of peace exist, not only within their own territory but throughout the world".[1051] It is important to remember that "it is one thing to wage a war of self-defence; it is quite another to seek to impose domination on another nation. The possession of war potential does not justify the use of force for political or military objectives. Nor does the mere fact that war has unfortunately broken out mean that all is fair between the warring parties".[1052]
501. The Charter of the United Nations, born from the tragedy of the Second World War with the intention of preserving future generations from the scourge of war, is based on a generalized prohibition of a recourse to force to resolve disputes between States, with the exception of two cases: legitimate defence and measures taken by the Security Council within the area of its responsibilities for maintaining peace. In every case, exercising the right to self-defence must respect "the traditional limits of necessity and proportionality".[1053]
Therefore, engaging in a preventive war without clear proof that an attack is imminent cannot fail to raise serious moral and juridical questions. International legitimacy for the use of armed force, on the basis of rigorous assessment and with well-founded motivations, can only be given by the decision of a competent body that identifies specific situations as threats to peace and authorizes an intrusion into the sphere of autonomy usually reserved to a State.
b. Defending peace
502. The requirements of legitimate defence justify the existence in States of armed forces, the activity of which should be at the service of peace. Those who defend the security and freedom of a country, in such a spirit, make an authentic contribution to peace.[1054] Everyone who serves in the armed forces is concretely called to defend good, truth and justice in the world. Many are those who, in such circumstances, have sacrificed their lives for these values and in defence of innocent lives. Very significant in this regard is the increasing number of military personnel serving in multinational forces on humanitarian or peace-keeping missions promoted by the United Nations.[1055]
503. Every member of the armed forces is morally obliged to resist orders that call for perpetrating crimes against the law of nations and the universal principles of this law.[1056] Military personnel remain fully responsible for the acts they commit in violation of the rights of individuals and peoples, or of the norms of international humanitarian law. Such acts cannot be justified by claiming obedience to the orders of superiors.
Conscientious objectors who, out of principle, refuse military service in those cases where it is obligatory because their conscience rejects any kind of recourse to the use of force or because they are opposed to the participation in a particular conflict, must be open to accepting alternative forms of service. "It seems just that laws should make humane provision for the case of conscientious objectors who refuse to carry arms, provided they accept some other form of community service".[1057]
c. The duty to protect the innocent
504. The right to use force for purposes of legitimate defence is associated with the duty to protect and help innocent victims who are not able to defend themselves from acts of aggression. In modern conflicts, which are often within a State, the precepts of international humanitarian law must be fully respected. Far too often, the civilian population is hit and at times even becomes a target of war. In some cases, they are brutally massacred or taken from their homes and land by forced transfers, under the guise of "ethnic cleansing",[1058] which is always unacceptable. In such tragic circumstances, humanitarian aid must reach the civilian population and must never be used to influence those receiving it; the good of the human person must take precedence over the interests of the parties to the conflict.
505. The principle of humanity inscribed in the conscience of every person and all peoples includes the obligation to protect civil populations from the effects of war. "That minimum protection of the dignity of every person, guaranteed by international humanitarian law, is all too often violated in the name of military or political demands which should never prevail over the value of the human person. Today we are aware of the need to find a new consensus on humanitarian principles and to reinforce their foundation to prevent the recurrence of atrocities and abuse".[1059]
A particular category of war victim is formed by refugees, forced by combat to flee the places where they habitually live and to seek refuge in foreign countries. The Church is close to them not only with her pastoral presence and material support, but also with her commitment to defend their human dignity: "Concern for refugees must lead us to reaffirm and highlight universally recognized human rights, and to ask that the effective recognition of these rights be guaranteed to refugees".[1060]
506. Attempts to eliminate entire national, ethnic, religious or linguistic groups are crimes against God and humanity itself, and those responsible for such crimes must answer for them before justice.[1061] The twentieth century bears the tragic mark of different genocides: from that of the Armenians to that of the Ukrainians, from that of the Cambodians to those perpetrated in Africa and in the Balkans. Among these, the Holocaust of the Jewish people, the Shoah, stands out: "the days of the Shoah marked a true night of history, with unimaginable crimes against God and humanity".[1062]
The international community as a whole has the moral obligation to intervene on behalf of those groups whose very survival is threatened or whose basic human rights are seriously violated. As members of an international community, States cannot remain indifferent; on the contrary, if all other available means should prove ineffective, it is "legitimate and even obligatory to take concrete measures to disarm the aggressor".[1063] The principle of national sovereignty cannot be claimed as a motive for preventing an intervention in defence of innocent victims.[1064] The measures adopted must be carried out in full respect of international law and the fundamental principle of equality among States.