A parishioner recently asked me what I thought of the current war in the Persian Gulf region. It was part question, “What do you think about….” and part answer: “You don’t want Iran to have a nuclear weapon, do you?” coupled with “and besides strategic bombing can probably bring this to an end.”  Not exactly an open ended question.

It is always of interest to me to wonder about to whom the question is addressed.  Was it for me, the Franciscan priest or former nuclear submariner or perhaps both? Then again, maybe that doesn’t matter. I think the answer will always come from “both.” Some might expect the Franciscan priest to take a position that war is always morally wrong. But Franciscans “think and breathe” with the Catholic Church, a Church that never places war as a first option but also evaluates each war in the light of the Just War tradition expressed by St. Thomas of Aquinas. So what is the “Church” saying?

One of the interesting features of the debate over the U.S. strikes on Iran is that there are respected Catholic scholars on both sides, although I would say that the majority of bishops and moral theologians who have spoken publicly have expressed serious reservations or concluded that the action did not satisfy the just war criteria. (Catholic Review) The limited number of scholars and intellectuals who have argued that the strikes could be morally justified have generally made their case on traditional Thomistic just war grounds, rather than appealing to a newer theory of preventive war (discussed later in this post).

George Weigel is probably the most prominent Catholic intellectual to argue that the strikes were morally justified. He contends that many commentators have misunderstood or misapplied the just war tradition. To that end he proposes three fallacies that people, leaders and scholars apply to Just War Theory:

• Fallacy No. 1: There is a “presumption against war” in just war thinking.
• Fallacy No. 2: Preemptive military action or striking the first blow is not permissible.
• Fallacy No. 3: “Last resort” is the first principle in the just war tradition.

Agree or disagree, but from that analysis, Weigel’s principal arguments for considering the U.S. military action as permissible include:

• Just cause: Iran’s decades-long sponsorship of terrorism, repeated attacks through proxies, and pursuit of nuclear weapons constituted a grave and continuing threat, not merely a speculative future danger.
• Legitimate authority: The United States acted through its constitutional political leadership in concert with an ally.
• Last resort: Diplomatic efforts had been attempted over many years and repeatedly failed.
• Proportionality: A limited strike on nuclear infrastructure was, in his view, morally preferable to allowing Iran eventually to acquire nuclear weapons or engaging in a much larger regional war later.

Weigel’s broader complaint is that many modern commentators have turned just war theory into an almost impossible standard that no military action could satisfy.

Edward Feser is interesting because he is a Thomist with deep knowledge of Aquinas. However, he reached the opposite conclusion from Weigel. Feser argued that:

• there was no objectively imminent attack on the United States;
• Catholic teaching does not permit preventive war simply because another state may become more dangerous later;
• the evidence for necessity had not been publicly demonstrated;
• therefore the traditional requirement of just cause was not met.

Professor Robert P. George of Princeton has been more cautious. Rather than declaring the war either just or unjust, he has emphasized a classical Thomistic point: outsiders often lack access to the intelligence necessary to make a definitive prudential judgment. The morality of the decision depends partly upon facts known only to those charged with responsibility for the common good. This echoes the Catechism’s statement that evaluating these conditions belongs principally to those responsible for the common good (CCC 2309), while still allowing scholars and bishops to question whether those conditions have actually been met.

Preventative or preemptive, the changing nature of war in the modern age, public demonstration of evidence, the common good – all these considerations. “What do you think about….” is not a conversation for the sidewalk in front of the church. And what about the Church?

I am not aware that the USCCB (US Conference of Catholic Bishops) have made a statement/analysis on whether the war is ad jus bellum (a just war at the beginning). Its statements can be found on the USCCB Iran Resource page. Reading them chronologically shows a remarkably consistent position extending back to 2015. Recurring themes include: support for diplomatic engagement; concern over nuclear proliferation; insistence that military force be truly a last resort; repeated warnings that another Middle East war would carry grave humanitarian consequences. The overall tone has been one of caution, de-escalation, and skepticism about the resort to military force, rather than an explicit declaration that the military action was or was not a “just war.”

But several bishops publicly argued that the criteria were not satisfied. Among them:

• Cardinal Robert McElroy argued that the United States was not responding to an objectively verifiable imminent attack and therefore lacked a sufficient just cause. (America Magazine)
• Archbishop Timothy Broglio, the Archbishop for the Military Services, expressed serious doubt that the campaign met the traditional just war criteria. (The Guardian)

At this writing there is no definitive statement but certainly, and always, a leaning into a peaceful resolution. Given my interest in World War II, I am drawn back to the comparisons with the Asia-Pacific War (1937-1945). In a previous post in a series about that war I noted that the Church teaches that war can be morally justified under certain conditions, which are rooted in the principles of just cause, legitimate authority, right intention, and proportionality. (Found in paragraphs 2307 to 2317 of the Catechism). The conditions fall into three broad categories: jus ad bellum (before the war), Jus in bello (during the war), and jus post bellum (after the war)

During World War II, Catholic moral theologians generally agreed that Germany’s aggression constituted a just cause for resistance. Likewise, Japan’s aggression in China justified military action. But were there adequate just-war reasons for the U.S. to enter the War prior to Pearl Harbor? While the U.S. was isolated from the war in Europe by the Atlantic Ocean, all throughout 1941 German U-Boats were attacking U.S. flagged merchant vessels as they carried supplies to England. The Pacific Ocean placed Japan thousands of miles from U.S. territories but Japan’s savagery and execution of the war in China, other Japanese actions against SE Asian countries, and more all signaled hostility with the U.S. was looming.  The questions being raised in 1939-1941 were:

• Was there a grave and certain threat? 
• Was it imminent?
• Has the last resort truly been reached?
• Could any U.S. action properly be characterized as defense, or was it a form of preventive war?

For U.S. scholars and bishops the theoretical debate came to a screeching halt on December 7, 1941 with the attack on Pearl Harbor and Oahu. What followed was broad and deep consensus that the U.S. action  met the criteria of jus ad belllum.  But could there have been military action before a direct attack on the United States occurred?

That comparison raises a profound Thomistic question that has never been fully settled: How should Aquinas’ requirement of “just cause” be applied when a grave threat is developing but has not yet become an immediate military attack? Can a preventative war be a just war?

Preventive War Theory?

If that was a valid line of inquiry 80+ years ago, what should the questions be in the face of the strategic and tactical realities of nuclear weapons, ballistic missiles, terrorism, and cyberwarfare? Is classical Thomistic just war theory suited to an age when the early warning signs of war are no longer months and years in the making but operate in the realm of the current moment. It is in this milieu that some theorists are thinking of new categories of jus ad bellum. To be clear, there is no accepted “new theory of preventive war” within Catholic teaching. Rather, there are several proposals by moral theologians and philosophers that attempt to reinterpret the traditional requirement of just cause. It helps to distinguish three concepts.

Aquinas never discusses “preventive war” as we might understand it. His concern is the restoration of justice after an injury. The assumption is that some wrongful aggression has already occurred or is occurring. This worked reasonably well in the Middle Ages, when armies required months to mobilize. It becomes much harder once weapons can destroy entire cities within minutes.

After 1945 Catholic theologians recognized that waiting until the first missile lands may be morally absurd. Suppose an enemy has fueled nuclear missiles, launch crews are at their stations, and intelligence shows launch orders have been issued. Must one wait until the missiles are airborne? Most Catholic theologians answered no. This led to renewed attention to the older distinction between preemption and prevention.

Although not Catholic, Michael Walzer has probably had the greatest influence on modern just war discussions. In Just and Unjust Wars (1977) he argues that there exists a point at which a threat becomes so imminent that waiting would itself be immoral. He revived what he called the Caroline standard, originating from an 1837 diplomatic exchange between the United States and Britain.  There the justification must be “instant, overwhelming, leaving no choice of means, and no moment for deliberation.” Walzer argues that modern technology may require interpreting “imminence” more broadly than simply seeing enemy troops cross a border. Many Catholic scholars have found this persuasive.

John Courtney Murray, SJ died before many of these debates matured but his work anticipated them. He emphasized that governments have a positive obligation to protect the common good. This raised the question: can rulers wait until millions are dead before acting? Murray never endorsed preventive war, but he opened the discussion about prudential judgments in an age of strategic weapons and more rapid response times.

After September 11 and especially during debates over Iraq, George Weigel argued that:

• terrorist organizations cannot be deterred in traditional ways;
• rogue states seeking weapons of mass destruction create a qualitatively different threat;
• therefore “imminence” cannot be defined only by troop movements.

He did not simply endorse preventive war. Instead he argued for a broader understanding of what constitutes an imminent danger. His critics reply that this effectively collapses the distinction between preemption and prevention. The critics include Germain Grisez, David Hollenbach, SJ, and Lisa Cahill.  During the run-up to the 2003 Iraq War, both Pope John Paul II and Cardinal Joseph Ratzinger repeatedly questioned whether the conditions for just cause and last resort had been met. Ratzinger remarked in 2003: “There were not sufficient reasons to unleash a war against Iraq.”  That statement is significant because it suggests the Vatican continued to interpret the traditional criteria quite strictly.

The debate in the late 20th century focused on nuclear weapons but today’s concerns are artificial intelligence, cyberwarfare, autonomous weapons, and hypersonic missiles. These technologies compress decision time from weeks to minutes or even seconds. Witness the recent AI initiated cyber attack on another AI system that was outside human control or knowledge until the need was done. The compression of decision time not only changes the debate on immanence, but has led some contemporary Thomists to ask whether Aquinas’ concept of injury should be newly understood as not requiring an actual attack, but in the view that an attack that is demonstrably inevitable, or the irreversible acquisition of the capability to inflict catastrophic harm.

Suppose a Catholic moral theologian in the 1930s had known that Germany would invade most of Europe and murder millions, or that Japan would initiate a campaign of atrocities in China and eventually attack Pearl Harbor. Would Aquinas’ criteria have permitted military intervention before those later aggressions occurred? That question sits at the heart of the modern debate. It is not fundamentally about preventive war as a new doctrine. It is about whether just cause should be understood as requiring a completed injury, an imminent injury, or an injury whose occurrence is morally certain.

From the standpoint of Catholic moral theology, what strikes me is what the USCCB did not do. The Conference did not issue a point-by-point application of Catechism §2309:

• Was there “lasting, grave and certain damage”?
• Had “all other means” been exhausted?
• Was there a “serious prospect of success”?
• Would the use of arms produce greater evils?

Instead, the bishops consistently emphasized diplomacy, de-escalation, prayer, protection of civilians, regional stability, and the moral presumption against widening the conflict. It has been their consistent approach to the 1991 Gulf War, the 2003 Iraq War, and earlier tensions with Iran, and now the 2026 conflagration. Those are good and true aims but there has to be a presumption of opponents not seeking a zero-sum solution. It seems difficult to think of those aims having the conditions of possibility in the USSR-Ukraine war.

So…what do I think about the current war in the Persian Gulf region. If the question is a “just war” question it’s complicated. The U.S. administration seems to be making a preemptive war argument which is a bit of a stretch even in a generous estimate. When asked in Congressional hearings no member of the administration would answer the question of whether there was a clear and imminent threat to the U.S. Is there a preventative war argument to be made – striking because an adversary may become dangerous in the future?

Iran is the largest supporter and financier of state terrorism as well as an advocate for the destruction of Israel and the United States. Do they have the means to match action with rhetoric? Are they an honest dialogue partner? And in an age when technology and cyber are collapsing the space and time between peace and war, is traditional Catholic just war theory suited to this era. That I will leave to better minds than mine.

What concerns me more is that the reports of the last five months from the Middle East are not good. By any measure, declared or not, we are at war with the nation of Iran. The last formal declaration of war, a power vested in the U.S. Congress, was made on December 8, 1941. In the aftermath of the attack on military installations on the island of Oahu/Pearl Harbor by the Empire of Japan, war was declared with a clear goal in mind: the military defeat and unconditional surrender of Japan. Since then our military has fought in military actions – without formal declarations of war – in Korea, Vietnam, Bosnia/Serbia Kuwait, Gulf War (Desert Shield/Storm), the Balkans, Afghanistan, Iraq, Syria/ISIS, and a range of actions under the umbrella of the global war on terrorism. And now, Iran.

Underneath all of this is the 1973 War Powers Resolution, commonly called the War Powers Act. The Resolution was enacted in 1973 over President Nixon’s veto in response to Vietnam and concerns that presidents had committed U.S. forces to prolonged conflicts without congressional approval. Congress sought to ensure that the President could respond immediately to emergencies, but Congress retained ultimate authority over sustained military operations. The Resolution does not grant the President new authority to wage war. Rather, it attempts to limit and regulate the President’s existing constitutional authority as Commander in Chief while preserving Congress’s constitutional power to declare war. The President may introduce U.S. forces into hostilities only in three circumstances: a declaration of war by Congress; specific statutory authorization by Congress; or a national emergency created by an attack upon the United States, its territories or possessions, or its armed forces. The 9-11 attacks met that political criteria. Does the current conflict?

Ironically, one of the principal criticisms of the Resolution is that, although intended to restrain presidential power, many presidents have interpreted it as implicitly recognizing that they may initiate military operations for up to 60 days without congressional authorization and then having another 30 days to report to Congress. The intent of this additional 30 days was for orderly withdrawal of forces from combat. The current Secretary of Defense reported to Congress as required and asserted that the report “reset the clock” for an additional 60 days of conflict. We are now approaching 6 months of armed conflict with Iran. There seem to be no guardrails.

The War Powers Resolution states that Congress could require the President to withdraw troops by passing a concurrent resolution. A concurrent resolution passes both houses, does not go to the President, and therefore cannot be vetoed. However, after the Supreme Court’s decision in INS v. Chadha invalidated single-chamber legislative vetoes, and the broader joint-resolution mechanism became constitutionally doubtful. If Congress wishes today to compel troop withdrawal, it generally must pass a bill through both houses; present it to the President; and likely overcome a veto with a two-thirds majority if necessary. Ironically, this makes it harder for Congress to force withdrawal than Congress envisioned in 1973.

Justice Byron White dissented vigorously to INS v. Chadha, arguing that legislative vetoes were a practical necessity. White warned that eliminating them would shift enormous power to the Executive Branch. Time has proven his prediction largely proven correct.

Aquinas insists that legitimate authority is one of the three essential conditions for a just war. But Aquinas does not specify how a constitutional system should allocate that authority. The American Constitution divides authority between Congress (declaring war, funding armies) and the President (Commander in Chief). The War Powers Resolution was Congress’s attempt to maintain that constitutional balance. 

Recent Supreme Court decisions seem to give increasing leeway to Executive Power and, for me, the question of constitutional balance is at the heart of the moral question. Regarding military action, we as a nation, seem to have reached a point where we are now reliant on the moral compass of a single person, the President of the United States, upon whom there are virtually no constraints. 

So…what do I think about the current war in the Persian Gulf region? We have no reliable moral compass that can operate effectively in this constitutional arrangement.  As a Church we have a moral voice and a duty to raise it, but I wonder if we have a Just War theory that is suited to the age.