The Just War Tradition and the Iran War

A Catholic Examination for American Conservatives

The Pope vs. the Secretary of War: A Theological Collision

On March 25, 2026, Secretary of War Pete Hegseth prayed at the Pentagon a prayer previously given by a chaplain before the Venezuela covert ops mission:

Let every round find its mark against the enemies of righteousness and our great nation … Give them wisdom in every decision, endurance for the trial ahead, unbreakable unity, and overwhelming violence of action against those who deserve no mercy.

Four days later on Palm Sunday, Pope Leo XIV (also an American) responded directly to ongoing conflicts and provided a foil to Hegseth, quoting Isaiah 1:15:

“[God] does not listen to the prayers of those who wage war, but rejects them, saying: ‘Even though you make many prayers, I will not listen: your hands are full of blood.’”

These two positions embody incompatible theologies of war. One of them is right. The rest of this article is about which one. This collision demands resolution for Catholic Americans and natural-law conservatives. While I am writing these words from my own perspective, it is these two main groups that I am addressing: Christians and conservatives.

Trump’s Own Words Reveal the Absence of Just Cause

President Trump on April 1, 2026, in what I hoped was a disgusting April Fool’s Day joke said of the war with Iran:

“We don’t have to be there. We don’t need their oil. We don’t need anything they have. But we’re there to help our allies.”

I’m glad he’s finally being honest about the supposed “imminent threat” to the United States that was bandied about as a casus belli. As a History teacher, the argument did not hold any water from the beginning.

Just cause in war requires self-defense or protection of innocents, not regional power politics. To be clear, I think that Israel does have a good cause for a defensive war with Iran given decades of Iranian belligerence, state sponsorship of terrorism, and abject hatred for the nation of Israel. Alliance solidarity is not the same as self-defense. The tradition permits war to defend the innocent, but the United States is not defending Israeli civilians. Some will argue that preventing a nuclear Iran is itself protecting the innocent—not just Israelis, but the entire region—and that this constitutes a just cause. The argument has force, but it was the justification for “Operation Midnight Hammer” in June 2025. The nuclear sites were already struck. What we are doing now is something else.

As far as the United States is concerned, the President confirmed that this is a war of choice, not necessity. “Operation Epic Fury” is prosecuting an independent air campaign against Iranian infrastructure on its own strategic timeline. Trump’s own language confirms this: we are there “to help our allies,” not to protect the innocent. This violates the foundational just-war criterion. For more on Just War Theory, please reference this little article I put together last year:

War is Hell: Just War Theory Explained

Last Resort was Never Attempted

In his April 1 address, the President said:

“My first preference was always the path of diplomacy, yet the regime continued their relentless quest for nuclear weapons and rejected every attempt at an agreement.”

Then, in the same speech he said:

“In the meantime, discussions are ongoing.”

So, which is it? The stronger point is not the rhetorical contradiction — a president can claim diplomacy failed and still talk during a war. The stronger point is the timeline. Iranian negotiators reportedly presented a proposal favorable to U.S. interests the week before Operation Epic Fury launched, and talks were expected to continue. Trump attacked anyway. “Operation Midnight Hammer” struck nuclear sites in June 2025, then full-scale war came eight months later with no evidence of sustained diplomatic effort between the two operations. If last resort means anything, it means you do not launch a war while your adversary is still at the table.

Legitimate Authority Has Been Bypassed

There is another just-war criterion that conservatives especially cannot ignore: legitimate authority. St. Thomas Aquinas teaches that the authority to wage war belongs to the sovereign charged with the common good (ST II-II, q. 40, a. 1). In American constitutional order, that means Congress. Article I, Section 8 is unambiguous. The War Powers Resolution permits presidential action without a declaration only in response to an attack on the United States and requires congressional authorization within 60 days.

Trump launched “Operation Epic Fury” on February 28 without a declaration of war and without authorization under any existing authorized use of military force (AUMF). The 2001 AUMF covers September 11; the 2002 Iraq AUMF was repealed in 2023. Neither authorizes a full-scale campaign against Iran, and no new AUMF has been passed. The administration has invoked Article II authority and self-defense, but the President himself gutted the self-defense rationale when he told the nation “we don’t have to be there.”

This is not a technicality. The just-war tradition requires legitimate authority precisely because the decision to spend human lives must not rest with one man. The Framers of the U.S. Constitution understood this. St. Thomas Aquinas understood it centuries before them. Conservatives who claim to value constitutional order and the constraint of executive power cannot simply wave this away.

Proportionality Has Been Abandoned

The criteria above concern the decision to go to war. The criteria below concern how it is fought. This war fails both tests. Also in his speech, Trump said:

“We’re going to bring them back to the Stone Ages, where they belong.”

When did this war become a war against the people of Iran? Trump’s own language answers the question. Unless we think the Stone Ages comment to be ambiguous, he also said:

“If there is no deal, we are going to hit each and every one of their electric generating plants very hard and probably simultaneously...we could hit [their oil] and it would be gone.”

Destroying the civilian infrastructure of 88 million people is not proportionate to any military objective and is wrong. This is total war against a civilian population, not constrained military action. It is reprehensible and gravely evil.

Discrimination Between Combatants and Civilians Has Been Obliterated

President Trump is increasingly treating the entirety of Iran as a unified enemy, not distinguishing the regime from the people. And to be clear, the Iranian regime is evil. This attitude is further evidence of a mindset shared by Trump and Hegseth. Hegseth’s prayer at the Pentagon does not distinguish between combatants and civilians. It sees the Iranians as not deserving of mercy. The way this war is being carried out violates a fundamental principle that non-combatants may not be targeted in war and civilians should be protected. Israel’s ongoing campaign in Lebanon, which has killed over a thousand civilians in four weeks, raises the same questions of discrimination and proportionality.

Do all citizens of a country cease to have human dignity because of the immorality of their leaders? We cannot accept that they do.

The Inversion of Christian Teaching on War

Just-war tradition says war always involves grave harm and should only be undertaken reluctantly under strict conditions. St. Augustine teaches that war can be just, but only with the right circumstances and intentions. Namely, the focus must be justice and peace, not vengeance. Hegseth’s prayer inverts this order. He sanctifies violence, treating it as righteousness. His clear desire is to maximize destruction rather than minimize it.

The First and Third Crusades were defensible on just-war grounds: they were responses to aggression and conquest, authorized by legitimate Christian authority, fought to recover territory under military siege. But the justness of the cause did not justify the conduct. The massacres, the slaughter of civilians, the denial of mercy to prisoners were all grave moral evils, violations of the principles of discrimination and proportionality. The lesson is crucial: a war can be just in its cause and unjust in its execution. What matters is that the entire enterprise, both cause and conduct, must be governed by justice and mercy.

Hegseth’s prayer inverts this distinction. It does not separate just cause from just conduct. It sanctifies violence itself. This is a false theology. It is not merely wrong — it is an inversion of the Christian tradition on war. The just-war tradition exists precisely to prevent the sacralizing of violence, to insist that even when war is necessary, it remains a tragedy governed by moral limits. Hegseth’s prayer collapses that distinction entirely, treating overwhelming force as righteousness and enemies as undeserving of mercy. Whatever we call this, it is fundamentally at odds with Christian teaching. I’d prefer to call it “idolatrous,” since it substitutes the will of the state for the will of God.

And it is worse than the excesses of the Crusades because at least those wars (the First and the Third) had defensible initial causes. “Operation Epic Fury,” by Trump’s own admission, does not. We are waging a war we do not need to wage, in a manner explicitly designed to destroy civilian infrastructure and reduce a nation to the Stone Ages. We are committing the sins of the Crusades—indiscriminate violence, denial of mercy, collective punishment—but without even the pretense of a just cause to begin with.

Pope Leo XIV is correct. God does not listen to the prayers of those who wage war in this way.

Why This Should Matter to American Conservatives Specifically

As a conservative American who (reluctantly) voted for Trump three times, I understand how difficult it is to see the world clearly through an American exceptionalist lens. We want the U.S.A. to be the good guys, to be a force for justice and democracy throughout the world. So, it is difficult to face the reality that what is being done under American leadership is very, very bad.

Just-war tradition is a conservative intellectual inheritance, through figures such as St. Augustine, St. Thomas Aquinas, Fr. Suárez S.J., and others. Just-war theory constrains power through reason and law, which is precisely what conservatives claim to value. This administration—which is populist, not conservative—has inverted that tradition, treating military dominance as moral license. Since 2001, questioning military action has been treated as weakness or insufficient patriotism. This has made it dangerous for conservatives to apply just-war reasoning to American wars.

The unconstrained executive power in military matters shown by this war is incredibly concerning to me as an American conservative. The just-war tradition demands more than application of abstract criteria. It demands witness. We can, and must, name this war for what it is: unjust in cause, unjust in conduct, and sanctified by a theology that is fundamentally at odds with Christian teaching. Silence is complicity.

The Proper Response: Examination of Conscience

Phil Lawler, in a March 13 Catholic Culture article writes:

“The just-war tradition is eminently practical, demanding, and thorough. Rather than providing quick yes-or-no questions, the tradition furnishes responsible government leaders with an examination of conscience.”

Lawler is exactly right, and he has practiced what he preaches. In his own Substack analysis of the President’s April 1 address, Lawler flagged the same passages I have cited here—Trump’s admission that “we don’t have to be there” and his threat to bring Iran “back to the Stone Ages”—and concluded that the first undermines just cause and the second threatens to constitute a war crime.

Pope Leo XIV’s call for examination of conscience is in precisely this spirit. The Pope is not telling Americans to be pacifists. He is telling us to be honest. Hegseth’s posture is the opposite: pray harder and don’t question what we are doing. The Pope, like Christ, invites us to examine our conscience.

We have to apply just-war criteria systematically: just cause? Last resort? Proportionality? Discrimination? Evidence suggests that the answers are all no. If a war fails the just-war criteria, it is not a just war.

This is not merely a foreign policy debate. And it is incredibly messy. The Iranian regime’s threat is real. That does not excuse waging war without just cause, without exhausting last resort, without proportionality, and without discrimination. The ends cannot justify the means.

The clash between the Trump administration vis-à-vis Hegseth and Pope Leo XIV is a question of whether or not the American people, and Catholics in particular, will allow leaders to wage war without moral constraint. Just-war tradition is a living inheritance rooted in Sacred Scripture. We neglect it at our own grave peril. Even war must be constrained by justice. The Pope’s call for an examination of conscience is a demand for moral seriousness, not weakness.

We can, and must, do better.

If you believe in natural law, you must apply just-war reasoning. And if you do, you cannot defend this war.